Sound likr you have found a total bargin. I'm jelous. Even beet up early Indipendents in full working order are worth way more than that kind of money. As for the engine, again no problem. All the 4trak deisle engins are basicly the same engine. The only diffrences may be:
1) there is more than one height of engine mount, however these just bolt to the block.
2) there is more than one type of terbo, and I don't know if the exhuste is in exactly the same position from one to another.
3) one thing I can't be sure of is wethere the sump is a diffrent shap on the Indipendent, to accomodate the fixed position diff.
But if you have the blown engine as well, non of these should be a problem, as the basic engine is identical.
As for looking underneeth. Obviously it's recomended, however there realy isn't much that goes wronge normaly. The chassis, axles, and gearbox are mostly so strong you won't need to worry.
The one thing the gearbox is known for is the main shaft nut coming loose. This is herolded by difficulty of selecting some gears (2nd and reverse first usually) and can develop into total inability to select any gear. However all that needs doing is to drop the transfur box off, and tighten/replace the offending nut.