The standard keyway and timing mark should be OK for the 3134 exhaust cam,and give the same exhaust timing as a 650:
Opens 55 BBDC,closes 34 ATDC ;measured at 0.020" tappet lift.
Lobe centre 100.5 degrees BTDC.
0.125"- 0.130" tappet lift at TDC.
If the lobe centre is anywhere between 100 degrees and 105 degrees BTDC,it will work fine.
Tell them to hone the cylinder bores with #180 grit,or even #150 grit,to give at least 0.0037" piston skirt clearance.If it's honed finer than #220 grit,it will be harder to seat the rings.It still pays to put no oil on the rings or ring grooves,just a drop on each side of the skirt.
Scrub the cylinders well with hot soapy water,before you fit the pistons.Oil them to stop rust,then wipe off as much oil as you can with a clean rag.The rag should still look clean,and not pick up any dirt when you wipe the cylinder.