The only way I see that IFS assy working is to substantially cut into your frame rails. Not necessarily bad, but a lot more fab work and more critical to get it right the first time. In essence you would leave the top of the stock frame and cut out the side and bottom to fit around the Jag crossmember. It appears your A-arm pivots will clear the frame. I would cut off the front bushing arms from the Jag crossmember. Weld it all in solid and add a few gussets for good measure and it could work. Access for working on the A-arms could be tight, make sure you account for future rebuild work on the front susp.

A lot more work than the 86 and earlier, but it could work. Do you have more time than money? If so, use what you have.