I posted a while back that I had bought a job lot of Tas P7 engines, I have found some things different between the early type and the later type.
Early type : O.R type pull handle, roller guide for pull cord, starter cover screwed from the back, short intake manifold, serial numbers P7- 2xxxx
Later type : Tas T pull handle, T Through pull cord guide, starter cover screwed from front, long intake manifold better balance factor crank,
serial numbers I have P7- 4xxxx.