I am on "Lotuswins's" team on this one H - stay with what you have and identify shifting problem.
Is your box stiff in all gears or predominantly the change from 5th to 4th?
Out of interest is the gear change stiff from 4th to 5th?
Yes this does seem like a lot of work for something that does actually work OK most of the time, especially on upshifts.
The box is very stiff on all changes, quite precise but very stiff. When dropping down from 5th to 4th, if you go 5th .... neutral .... 4th it usually goes in OK, but if you try going quickly straight down into 4th, it seems as thought it hasn't gone through the gate into the 3rd/4th plane and you're trying to go where there is nowhere to go - a bit embarrassing when you are taking a paying passenger out on a charity ride.
I know this will sound like I can't actually drive my own car, and there probably is some of that I'll admit. When I first had it I took it to one of our Specialists for their expert opinion, expecting them to say "it's a load of "You-know-what" " but as he got out and came to me he said "Actually, it's one of the best I've driven" which deflated me quite a bit.
I suppose that I'll have to re-learn double de-clutching all over again and just take things a bit slower and get my down shifts sorted well in advance?
Thanks for these answers, I was hoping that after eventually finding a 'box it would be just a question of fitting it and adjusting the linkage a bit, but from what you guys have said it's so much more than that.
Ok now onto the next bit, rebuilding the engine!
H.