Engine?

[Kim57]

This is a 3 part question.
I'm building a 57 chevy pro-street themed P.U. and am considering going one of a few ways on the engine trans combo.
My frame has a 67 chevelle front clip on it.

#1 - 454 vortec pulled out of an 99 truck. This engine has 90,00 miles on it so I will have to go through it and freshen/replace what is worn out on it.
On the plus side it has all the accessories and brackets on it.
It also has the multi port FI and comes with the computer to run it.
Is this a decent FI for the street?
Is there a way to tell if it has 4 bolt mains and a forged crank without pulling the pan?
I can get this engine for $1,000.
I would need to get a trans for it, possibly a 4L80.
this seems to be about the most cost effective way to go if the stock FI will make some decent power.

#2 - I can get a 6.0 LS2 out of a 2009 SS Trail Blazer with a 4L60 trans and computers. This is supposed to be a 390 HP motor. Only supposed to have 18,000 miles so it should be good to go.
I will have to change some things to make it fit my frame so that will add to the overall cost.
My biggest concern with this route is if the engine trans isn't what it's purported to be. This could end up being a costly rebuild.

#3 - I have a new 4 bolt 454 bare block that would have to be built from the ground up.

I'm just looking for a cruiser that will have decent power and not brake the bank getting there.
I'm leaning towards the BBs because of all the room in the engine compartment on the truck but the fact the LS 2 has the trans makes it tempting.

Sorry for the long post.
I do appreciate any info I get.
Kim