Think it was member ohio hoss did some on his. Summit used to sell crate engines that way. Quick way of boosting up compression for a street use setup. The H.O. heads were the best flowing 305 heads & they respond well to porting & a good 3 angle valve job.
As common sense would tell you , they would start choking up at high rpm compared to a good larger head, but with the right combo could produce good low end torque & decent hp.
I know 225cc AFR heads are out of your budget also, so what the heck.:beer:
No way would I trade. The 305 heads will raise compression if that is all you are looking for. The small chambers have small valves in them. I have a CHP article that lists flow numbers, stock and with a lot of work done on them. The numbers are dismal, the Vortecs will easily outperform them. Fine for a 305 but you are strangling a larger engine. If you want more compression, buy pistons.