Hi,
Principle of long stud conversion is to reduce stress of block.
All holes of crankshaft maincap are in line with holes of head.
6 holes on the block are drill trough the block and fitted with 6 long studs
All 4 other (2 on each end of block) are fitted with "standard short stud"
On this way, on central long studs, the stress of tightening is supported by studs, not by thread on the block.
Machining block is necessary, by specialist.
Regards
Claude