Mazda B2200 1991

I am dealing with a problem with stock engine..
I have the stock 5 speed tranny.
I am blowing headgaskets and want to change engines..
Do you know how i can find out what engines will bolt up to tranny in my 91 mazda b2200?
I am lost...
If you know which engine maybe you can tell me what car it came in..
Thanks so much..
spokaneman@live.com