Look at S10 and the Dakota or Durango frames. Dakota or Durango frame would most likely be the best depending on the width since of the mtr combo you want to use. Both are used a lot under all kinds of trucks & there are brake/suspension upgrades if you want or need them.
Also if you enjoy reading you could look through this post over on HAMB is a HUGE post of S10 and other frame swaps...joe