318 head porting for the average joe

I wish I could have found a set of 920s..... but since its been over 50 years since they were made, I doubt it would be very likely that ID be able to.
I want to port the 302s but I'm almost afraid to now that they have been thru the machine shop/ I may try it anyways while I'm working for teh one on my /6. That one is in line still for the machine shop.