T5 will be about the best 5 speed you will get for a decent price. Will live fine behind a mild-strong 253.
lol ive destroyed T5's with a red 179 HP. the phillipino 4 speed i had behind it in the end was tough as nails...that pic u have looks to be the alloy case celica 5 speed...i happen to have a steel case if your interested
(no bell housing/yoke...just the box & shifter) they are a good box man, but like any box, they will only survive as long as you let them. whats wrong with the m21? 2nd and 4th is longer than that of a T5 and so long as you weld the shifter up good and keep your linkage setup tight you shouldn't have any troubles.
lol @ 1400 hp+ from a 253....