by kitabel

Missing from this advice: the first time either piston approaches TDC the dome will crash the head, and a valve may strike the dome.
Why?
Because the panhead barrels are .200" shorter than knucklehead (5.33" vs. 5.53"), which reduces your piston to head clearance by .200".

Oooppsss...

What to do?
Insert a 3/16" stroker plate and an extra gasket to get the math back to nearly stock.