63 cc's for the 60779 closed chamber ones and 65 for the 60179 'open chamber' ones. You have to use a combo of head AND head gasket like I listed to make the clearances work, AND do some measuring.
If you are not comfortable with measuring things and setting clearances, then don't go down this road. I just wanted you to be aware that it can be done with the right parts and measurements. The warnings to not use Edelbrock heads with the KB190's are for the knuckleheads who just want to slap things together.... that WOULD be problem!
DCR is what you care about; SCR is just part of what goes into DCR. The numbers I gave you are worked out for a 282 cam. If I plug in your xe274 cam and set the cam timing for dot-to-dot timing, then DCR comes up to 8.3. Still quite manageable with quench and AL heads, and it's not all that different from what you have now with that cam and piston and head combination and a thinner head gasket; I think you have around 8.0 DCR right now. Care in tuning IS required either way. But the idea to go to a larger cam is to get even more top end HP and use the larger heads better. You have the pistons to support that.
