Engine Build ?

[85/Silverado]

I have a guy building me a Stroker 350 chevy motor, I know it won't be a 383 he said it will be different.. Anyways the question is he said he is having a special Crank built to change the firing order for better cooling..

{By swapping #4 and #7 cylinders in the firing order, this eliminates the fuel distribution and heat problems caused by cylinders #5 and #7 firing in succession.}

I was wondering if anyone else has done this?

I already bought the Vortec Heads 200cc intake runners, 64cc combustion Chambers,,, 2.02 stainless intake,, 1.50 exhaust. So the heads are the best I could fine.
And Edelbrock 7116 Vortec Pro. RPM Intake.
Not sure how big a carb I should get 650 or 750?