'90 4.0 cam upgrade

with 300 km's on the wreck and oil coming out the rear seal faster than a tap its time for a new short block.no stroker,just stock with a cam upgrade. rumor has it you can use a cam from a '97 0r newer TJ. is that crap?

You can use a 4.0 block of any vintage. The only problem you'll have if you're using a '92+ block is finding a pilot bearing for the crank to match the input shaft of the '90 AX15 if you have that tranny. If you have the AW4 that's not an issue.
As far as cams go, if the engine's going to remain otherwise stock internally, I recommend the Crane 750501 cam to maximize torque at low/medium rpm. You can get it from Summit Racing under part no. CRN-750501 for $204.69. You'll also need Crane lifters CRN-99278-12 at a cost of $68.99. You can use the stock valve springs/retainers with this cam so that'll save you a few pennies.