Well when forced to stick to a stict budget I would not spend any moeny on stuff that won;t help that much.
I would freshen up the 307 with new rings and bearing and a cylinder hone job.
(do not bore for new pistons.) If the 307 crank is not pristine get it turned .010- .010
I would find, hand home port and use a different cylinder head with a small combustion chamber (53 to 58cc) on that 307 and use the SR torkers on something else.
Otherwise the engine is going to have a low compression ratio using those 67cc heads.
Use the 4416 heads off your 305, on the 307. (If your 305 has the good #4416 or #601 heads, use 'em)
Port them, Don;t be shy here add 1.94" intake valves and get a valve job and some perf valve springs.
CC them and mill to 56 to 58cc actual measured.
use a felpro 1094 steel shim head gasket.
750 carb dual plane RPM style manifold,,, headers... recurved HEI
get some gears for the car and a converter. A 10" "3500+ stall" is not too much behind a 307. (actual stall will be closer to 3000 rpm) 4.10's is great.
The erson cam will work very well in your 307 if moddied like I outlined. You want as close to 10:1cr as possible.
It will surprise you in how well it performs. But the details matter.
Use the 67cc 2.02 S/R torker heads on a 350 or .... The chamber is just too big for a 307. (unless its a supercharged 307)
Last edited by F-BIRD'88; 04-09-2013 at 02:43 PM.