I'm not familiar enough with the L gearboxes to say 100% on your last question, but being that the 52 and 43 were used in the same generation of truck, they should interchange.
Crawl underneath the truck and look at the mount. You'll be able to tell if it's the same. Toyota mounts are often interchangeable too, so the mount on your 4-spd should fit your newly acquired tranny.