Vortec heads are great work horses. If you drive and use it as a service vehicle they offer daily driver performance and reliability. My 906 vortec heads were $200 for the pair. With that, the yard let me grab 16 beehive ls6 springs from series 2 v6 engines. Some forum member passed on this head recipe as good. It worked better than many aftermarket head packages. The springs are around 300 open, 96 closed, and have the small retainers. The factory vortec roller cam is around .420 lift and if you use it with a performer flat cam it works great. My oppinion is that the performer cam and vortec heads is the best , cheapest way to get the most for the least. No head mods nesscary. If 67cc is to big go to napa and have the machinest do the milling on the side or after hours. It will save you some cash and doesnt hurt to ask. My heads were milled to 60 cc for less than $80.
You can find a 3.73 gear set for cheap to. A 3000 stall would be a acceptable road peice. Then you could do nice burnouts and seat planting launches.