Rebuilt and just fixing is two different things. The synchro is almost always bad unless it has been recently replaced. The input shaft is quite often chewed up where they engage the synchro. Second gear quite often shows a lot of wear and that affects your shifting. The top shaft shift fork catches a lot of wear too. The low and reverse slider can look pretty bad and not make any difference. I paid $250 just last week for a 1952 and older synchro. Cletis sold one on eBay several months ago for around $100, but I missed it. 53-54 synchros have generally been easier to find and 2 of the lugs can be ground off with a die grinder. Add $100 for the 2 ball bearings and small parts, and $800 doesn't look that bad if it is done right.

A pickup case is a little shorter than a passenger. The 591615 casting will fit 48 through 54, but the 53-54 has different gears.