Budget 318 build

IMHO, it would take a LOT of porting, plus valves, in the 318's to match the 360's.

Yes, there are flathead/nailhead valves that will reduce the chamber volume by about 2 cc's. But that is a low return on the $$ spent. You will get far more out of the

The parts are not well matched for your original stated goals. The cam and CR and stock TC combination are going to leave a flat spot at the low RPM range, regardless of the rear gear's improvements. The result will be to hit the gas, and then wait for the engine to rev up; the stock TC won't let it immediately get up in the torque band. Plus the torque band will be up higher, which drives to the cost of valve springs, etc.

Let's go with the thought that you deliver pizza's in the evenings for a few weeks and make the $150. How to best spend that?

• Mill 360 heads. Gets CR up a bit which helps the low end some. Still have the cam which is the primary item that will set the engine's characteristics and the cam and head runner volumes don't match up well with the TC and CR for your stated use.
• Port 318 heads yourself and mill. Helps the CR even more. Helps with DCR and also the smaller ports are better matched to the use you have stated.
• Buy new cam and sell old. That is the winner, IMHO. Then match it with the 318 heads that are ported by yourself. I'd STILL like to mill the heads for better CR, but that is beyond the $150 limit. Deliver more pizza's?
• New cam, sell old, and mill 360 heads? Probably the best. Deliver more pizza's.

Seems like the REAL solution is to deliver pizza's for a while LOL!