Hi Dave
I'm really glad to hear your hand's sorted and you can get back to modelling.
Tamiya kits are famous for their well-fitting parts, but the fuselage halves of my own copy of the Meatbox are slightly bowed, needing pressure to close a gab along the top joint. It's a tricky joint, because the opening for the wing is so big - using a rubber band around the fuselage will probably start forcing the joint open again.
Two approaches might work:
1. Use a "hot" liquid cement like "EMA Plastic Weld" or "Tri-Tak", so things set quickly. I'd do as Tin Can suggests and use finger pressure to begin with, and then strap the joint with some tape, once the cement had begun to cure.
2. Join the nose and tail normally and let them set. Then pinch the joint closed and let capillary action carry thin CA along the inside of the fuselage. Finish off with some liquid cement if necessary.
Good luck.
Rowan