What is your bottom bracket height? (floor to center)

thanks hippy - but bear in mind this is likely easier said than done for me rght now...bu i'm sure i can get the hang of it.

Could also look at restoring the original wheel set (27") with a fixed hub to give a bit more height also (albeit only 4mm i think), + higher tyres, and maybe i can find a suitable 160 or 165 crank to go with it (but by the time i've fucked around with all that I might as well buy a frame)!

I would stay with the 700c wheel. I had a 27" wheel set for a short while, and getting quality tires locally became difficult.

A better way to raise your bottom bracket height might be to replace your fork with one that has a greater axle-to-crown length. Or you could modify your existing fork to have less rake. Most shops should be able to help you do this for less than the cost of a new fork.