If you don't have the cash to get everything you need, I would hold off till you do. Do a basic rebuild and start saving to build a 4mil later down the road. If you cylinders are nearing the end of their life, buy some 64mm cylinders and start with those. Piecing together a 4mil isn't worth the hassle in my opinion. To truly get the benifit of running a 4mil motor, you need EVERYTHING to be correct. That list of parts can run you well into 2grand depending on what you have to start with. Don't half ass it, talk to a builder and do it right the first time. You will need the following:
4mil hotrods crank with 115mm rods.
Wiescos
port job
Cool head with domes cut for the extra stroke
Carbs and filters
Timing plate
Intakes
Pancake
Billet basket
FAST clutch
Port matched cases
Gaskets and seals
That is a complete 4mil build. Depending of what kind of power delivery your wanting you may also need pipes. You will want to do the shifting mods as well.