There is no 'problem' swapping the rod There are a few 44.5mm pistons out there.
Maybe not for you Lozza, but to most of us it's a major undertaking. Not everyone has the expertise or equipment to do crank rebuilds in their suburban shed.
Google 'crankshaft rebuilding services' and $50 and a week or so later you have a rebuilt crank with 0.00mm run out on a single, twin($90), triple($120) or 4 cyl($160) press up crank. I don't bother rebuilding them myself now unless it's rush rush.
Evo I have the KX rod dimensions but not the LEM, I do have the KTM 65 rod dimensions