Another thing that you could try out (just to be absolutely certain that you're doing a good job) would be to buy a set of new standard size rings and then push one down into to the bore. If the piston ring gap is excessively large (definitely anything over 3-4MM or so), buy the next size up and then file the ends down slightly so that they're a tighter fit - don't forget that the bores are tapered, and are slightly narrower towards the bottom of the block. I simply deglazed, and fitted all new standard parts to my N/A (all Britpart) and I didn't remove the ridge, or fit ridge dodgers either. I've had the head off three time since the rebuild for other bits and bobs and it's running better than it ever has done now. The Britpart pistons and rings are also all still in one piece with no cracks!
-Pos