With 100 cc heads on a 350 size motor it will take a pretty good dome on the piston top to get compression where you want it------biggest issue it the different valve locations/angles-------you'll need pistons that will clear both sets of valves

A roller cam is piece of cake-talk to one of the cam companies and have them grind you what you want for use of motor-------might have a problem will cam cores so you may need to regrind it on one of your old cams-----