Does the 307 in the 83 H/O have the roller lifters or is this only on the 85 or later?

 

Nope

 

Roller lifters started in '85 for the VIN Y engines (plain Cutlass) and in '86 for the VIN 9 engines (442). So all '83 and '84 Hurst Olds (and '85 442s) had flat-tappet lifters.

 

pretty sure it goes flat tappets 5A heads
6A-7A heads = roller

 

Yup. And along with the 5A heads you got the cast iron exhaust manifolds instead of the later tubular steel manifolds.

In my experience, the earlier 9-code engine performs better than the later one. I don't know if it's the heads, exhaust manifolds, or maybe the cam profile.

 

All the above plus a touch more compression in the early 307. Olds 307 HO was the hottest 5L in 83, by 87 it was 55 hp behind the Ford 302.