Cylinder Head Bolts

Managed to get an engine block for a Zetor 3511, however the cylinder bolts are a smaller type than the old one. How can i get around this, can my old cylinder heads still be put on to this block with the smaller diameter bolt ? or will i have to bore the block to fit the bigger bolts ???????????. The engine block numbers are the same , a 3001 engine.

The early engines used 14mm head studs, later engines 16mm. Just centralize your later heads on the smaller studs & all will be fine