I've built a few of those, and found them to be slightly oversized over an engine casing. My 2cents, based upon what I admit to be a personally vague understanding of your question:
If it's only a gap of 1/2, to 1 milimeter of the printed part of the cardstaock not meeting up, switching to 65 may give you that much, but once again, and just going by what I'm reading; if you haven't done so, try other engine casings, and double check to see if you're printing out the model with an 'ACUAL SIZE' type setting, and not a 'FIT TO PAGE' or other.
If you can't get even the glue tab portion of the body tube to meet up again with the paper, when wrapped around an engine casing, it definately seems to be a sizing issue related with printing.
If it's printing to actual size, and your casings are good, (consistant) you could try increasing the print size to say, 102%?
Eric