AFR heads with stock L31 intake?

[jimmyve2]

Thinking I might throw together a very mild 383 for my 99 suburban. The 350 keeps having unusual misfires under heavy load only, and I'm leaning towards a slight head gasket leak between 3 and 5 or slightly burnt valve on #5.

Nothing fancy really, it will be a mostly stock type build as I'd prefer not to have it tuned if possible.
I'll get a cleaned and milled lower intake.
Plenum spacer if I can find one.
I'm thinking a stock LT4 cam to get it away from the truck powerband.
9.5-ish:1 compression.
Stock replacement headers.
Catless downpipes, already have true dual 2.5 from cats back.
AFR enforcer heads are most likely going to be the winning head choice.

Now I can't bring myself to put stock heads of any kind on this thing. Even if vortec heads are the best stock heads, they are still very restrictive compared to pretty much any quality aftermarket head and good remans cost about the same as the AFR heads.

My question is fairly simple, the enforcer heads are drilled for both intake patterns. Will the stock vortec intake ports line up properly to the ports of the heads? Or should I just get the summit "Vortec" iron heads with bigger valves than stock?
I know the vortec port shape, height and spacing is slightly altered compared to the earlier style heads.

 

[Schurkey]

Thinking I might throw together a very mild 383 for my 99 suburban. The 350 keeps having unusual misfires under heavy load only, and I'm leaning towards a slight head gasket leak between 3 and 5 or slightly burnt valve on #5.

A cylinder leakdown tester would tell that tale.

Nothing fancy really, it will be a mostly stock type build as I'd prefer not to have it tuned if possible.
I'll get a cleaned and milled lower intake.
Plenum spacer if I can find one.
I'm thinking a stock LT4 cam to get it away from the truck powerband.
9.5-ish:1 compression.
Stock replacement headers.
Catless downpipes, already have true dual 2.5 from cats back.
AFR enforcer heads are most likely going to be the winning head choice.

The GM "crate" 383HT is pushing the stock tune. Compare your cam 'n' compression to that engine. If you're beyond the 383HT specs, you'll need tuning. You probably should have tuning anyway.

My question is fairly simple, the enforcer heads are drilled for both intake patterns. Will the stock vortec intake ports line up properly to the ports of the heads?

You should contact AFR and ask 'em. Even a good photo of the intake ports might suffice.

 

[99xcss4]

good luck getting a manifold/plenum spacer used is the only option right now if you can find some one who has one. if I was in the market for vortec heads I would get these https://www.summitracing.com/parts/afr-0912 or these https://www.summitracing.com/parts/pmx-2151 I also agree with the ht383 comment. I would also add if you are going to get new pistons get flat tops with 2 valve re-leaves you will get more compression the the stock one that have re-leaves on booth sides of the piston. I would not change the power-band too much if you plan on doing any towing/hauling or going offroad