Mini Gearbox Question

[alastair]

Hi guys,

I have a metro turbo mini running approximately 120bhp which I use both on the road and on the track and do less than 2000 miles per year.
When I first ran it a number of years ago I ran the original helical gears but changed the drop gears for 1:1 straight cuts and put in a 2.76 final drive. This gave me great acceleration and good top end speed. However, a few years ago when I was driving it steady after just replacing the engine and gearbox gaskets the gearbox went bang when I tried changing from 3rd to 4th. The 4th gear and corresponding lay gear gear had stripped half of their teeth. The rest of the gearbox was in tact and looked fine (no scoring on the gears and all the teeth intact without any visible marks.
I took this opportunity to fit a set of straight cut close ratio gears and a 3.4 final drive. This is fine for short tracks, but is rubbish on the road as it is hard to pull away without slipping the clutch and the top speed is lacking somewhat in relation to the previous set up.
I currently have the gearbox out and I am planning on putting the original set up back in.
The question I have is should I re-use the old gears (1st, 2nd, 3rd) as they look fine or buy new? If I do re-use them, will they match up with a new lay gear or wear out really quickly? Obviously I will use new baulk rings, bearings etc throughout.

I have pics of the old gears that I can post if that helps.

Cheers

[Moleman]

Sorry mate I can't help but there must be someone on here who can?