EASY to build, but..... First question is what kind of fuel are you going to run. 500 naturally aspirated HP from a 4.030" bore 383 with a stock 23° head, on pump gas, is going to be borderline street friendly compression. Be cautious what you build here. I have been down the road of building a killer combination that sat in the driveway because I finally realized the $30 worth of C-12 fuel it cost to warm the motor and drive to the store for a $2 loaf of bread was pretty much foolishness.
But... here's one opinion and pump fuel, street friendly combination.
Here is 488 SuperFlo Dyno proven pump 91 octane HP from a 383:
GMPP 4bolt casting (these are only marginally better than a production casting, but I have 2 out there that have been in the low 500HP range for the better part of the last decade. )
QUALITY and ATTENTION TO DETAIL will make a big difference in resulting HP, everywhere you cut a corner, cuts power and or reliability. Remember that.
Make sure you machinist rough clearances the block for the 3.75" stroke, and hones to final size for the forged pistons with a torque plate (generally adds $100 - $125 to the boreing cost) Get the deck cut to 9.000", and squared to the crank centerline. Lots easier to make compression with the anti-detonation advantage of a zero decked motor.
Over and over and over again I've said,, HEADS ARE WHERE THE POWER IS MADE. Scrimp here and you jepordize results. You need a head that flows close to 300cfm, but more importantly one that maintains a decent port shape and volocity for the low RPM street driving. AFR is stellar in both departments for a street / lower HP race motor (as in < 600 n/a small block HP) motor.
A set of box stock AFR 210 Race Ready (I think they call them "eliminators now) will flow enough for a 500HP 383 spinning up into the 7K range easily. The AFR's are a NICE street piece, but I'm the kind of guy that can't leave 'good' alone. Besides, you will want them cut to 69-70cc to set compression. I had them angle milled to 69cc, intake face and bolt bosses corrected, (added a couple hundred $ but the small benifits are worth every penny in performance and reliability of gaskts)
You will need to replace the valve springs with the right spring for the cam, so have Tony build your set minus springs and reteiners / locks,,, (OR, They will put 'your' spring on if you get them to him for the build. (AFR offers a shelf stock Hydraulic roller spring.,, PASS on those, There a budget spring and you need a little over 400-425psi on the nose, their spring is about 40psi too soft for this cam)
Shaun (Super73) and I have a running 'discussion' on Hydraulic roller cams / valve train and their RPM limiting weights. He proves me wrong in a number of areas, so valve train is probably more of a overkill preferance to keep things light and reliable here. But it works for me so take this as ONE OPINION.
The AFR 210's use a 1.55" spring, and you want one that matches the cam, and has at least 425psi on the nose. We'll discuss that with the cam, but the rest of the valve train needs to be LIGHT, and RELIABLE. Any junk you interject here could be the piece that cost you the motor at 7000rpm.
I run Morel hydraulic roller lifters,, and
ONLY Morel they can be a pain to hunt down with everyone claiming theirs are Morel, but they are the best of the best. Settle for none less.
Pushrods in a standard 5/16" chromoly will work at these lifts and spring pressures. Don't think a stock pushrod with pressed in ends is going to survive, Comp and Crower has a decent line of pushrods. You will need the RIGHT length for your valvetrain / combination. If you don't have a pushrod legth checking tool, find someone who does. You need one here. Pushrods are sold in 0.050" lengths + or - from stock length. Your pushrod checking fixture and micrometer to measure doesn't need to be any $500 tool. If you measure and calculate to the nearest 0.001" , you can still only order pushrods the nearest 0.050" standard length. You get the point.
Comp also has a very nice 1.55 titanium spring retainer and locks. Again, weight is a BIG concern IMO,,, I've seen a lot of things go wrong in the valve train (i.e. broken spring at 7000) and the Comp retainers and locks hold pieces in place. You get what you pay for here IMO.
When Crane shut down I paniced and bought a stash of Crane Gold Race rockers. For a stud rocker they were the lightest, most accurate, reliable and durable I found. I have heard Comp filled in the gap with a good stud rocker, and guys on the Bullet are talking YellaTerra and HarlandSharp as replacements. Not much I can offert there,, sorry still using up my 'stash' for a stud rocker motor. Crane is back in business and after the S&S ordeal,, I don't even know who owns the name now. Just be cautious and do your homework on what is a LIGHT, quality aluminum stud rocker (AFR's are 7/16" stud BTW)
Rotating assembly:
Work calls,, more to follow