I have found that depending on whether the engine was assembled at the factory or assembled from parts usually gives different timing figures. I think there have been some running changes over the years with regard to timing profiles and such.

This engine was assembled from parts from several engines. The piston/liner was a retail packaged matched set, and the rest came from chop shops or my spare parts box.

Box stock canvas:

Crank bore: 7.6mm
Crank inlet timing: 34/63
Carb choke: 6.15mm (Traxxas carb)
Exhaust timing: 84/84
Transfer timing: 65/65 (a bit advanced for an RTR engine)
Boost timing: 57/57

Modified canvas:

Sirio conrod swapped in place of OEM conrod.
Crank bore increased to: 8.5mm
Crank inlet increased to: 32/64
Crankweb and counterweight re-profiled and lightened
Carb swapped for a big block .26 engine: 7mm choke
Exhaust port widened and timing increased: 88/88
Transfer ports increased to: 67/67
Boost port unshrouded and timing increased to: 60/60
Piston lightened and modified to unshroud boost port
Crankcase modified to flow better between transfer and boost ports
Starter backplate modified - phosphor bronze gushing removed and replaced with three ball bearings.

Thats about it. I am going to try getting this engine broken in and thoroughly tested very soon.