I was referring to the L20B and I'm aware of the engine mount issues. The J16 came in the us marked 620 and 720s. The J18 was a mexico/central American marketed engine. you can find them but it's difficult. The 5 speed came in the 510 was fully synchronize.
In the interim. I'm just gona get the J13 running good and drive it as is. I'm also on the fence about shoehorning a KA24DE or an NA SR20 with a S15 6spd. But who knows.... We'll see what the future holds.
Thanks, Nick