Thanks Grumpy and Bigted.
Well I could just, barely, turn it over by hand, that is without the flywheel, so used a socket. Later when the flywheel was on I could turn it over with that, but it did seem tight.
I did oil the rings, bore and piston. Good to know I can use a drill to check spark etc. when every thing is going freely.

Yes Bigted I did check the ring gaps and they were within limits (just) .08 from memory. I put one ring at a time in the bottom of the bore and made sure it was square, using the piston with a ring in the bottom ring groove to push in.
Will take out the ring expander in the morning, recon you've 'hit the nail on the head'. Will double check all tolerances.

Terrific advice gents, am very grateful I can go on with the project tomorrow with renewed confidence and gained knowledge.