Jed,
Remember that just changing to a 4 barrel intake and carb. will not make much difference in power. The crank, cam, lifters, pistons, rods, heads & ports & combustion chambers and distributor timing may all need to be changed if you want better performance.
The 273 engines had forged cranks and solid lifters but the 2 barrel engine components were different than the 4 barrel engine components. Also, rebuilding a 273 may cost more than switching to a 318, 340 or 360 engine.
Sorry if you are probably already hooked as a hot-rodder, join the club.
