Discussed a zillion times the SilllyKa T50 Hence conversions are always 4 sale.
First gear runs out faster than elevator victims of Pavarotti passing gas.

3.25, 2.9 first is where its at starting with most 71 nissan boxes, followed by T5 & then steel case w50. T50 in a light car & big hp only good starting in 2nd.

The cheapest option for a good ratio box weve found with another member is an A series auto bellhousing with 5mm steel tapped and bolted to an S-10 WC T5 box. Front input shaft is removable and T5 would never break. Would prefer a smaller RWD box with separate bellhousing, longer input shafts that can be easily machined to suit and lightweight with good ratios is a big challenge and rare.