101.6 (4") is the pitch circle diameter.
The radius is 1/2 that.. =50.8mm (2")
Just draw a circle 4" diameter and then adjust a pair of dividers to step out 3 equal divisions around it...
Even if you are 1mm or so out, the long bolts will still fit, just drill the holes in the plate to 11mm for some clearance.
[edit] note all the other holes in my puller there- are used for pulling flywheels off 70HP and 115HP OMC outboards, and other things.. once you have a solid puller you find other uses for it.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.
