Cab is absolutely right, you MUST check the clearance to be safe. Not just piston to valve, but retainer to guide and coil bind as well. As an example the Comp 284 XE in my 'Cuda was one whole tooth off when it we checked it. First degree the cam in then check the clearances. Since you want to use a hydraulic cam you will need two solid lifters to check with. If you don't have any solids it's easy to convert two old hydraulics into solids for checking purposes. Just gut them and cut some round stock [ bolts work fine ] to the correct length and replace the hydraulic guts with it and replace the pushrod cup. DON'T try to simply pump up the hydraulics and hope for the best. Keep in mind that while you can check piston to valve clearance for depth with the heads on it's all but impossible to check radial clearance. Of course since your pistons don't have valve reliefs this dosen't really apply in you particular case. Take the time to check, it's good insurance. As for cams you might want to try a Comp 275 HL.