frame jig

First off i have already built a 3/4 sfbd frame for my blazer so i know the basics

Now to the question my next project is a mazda b2200 but i wanna do a s10 front clip with a 3/4 frame. i only have one problem after i jig the mazda's body mount locations, tranny mounting location and wheel base what is the best way to put the s10 clip up make sure it square and the front wheels are in the same location as stock?

I'm tired so im not going to go into every inch of detail but a basic idea would be to find a good point on both frames for where u will be cutting both off and measure from that point to the center of the wheel. But before you completely box and weld the new clip i would test fit the fenders back on and make sure you are centered if your barely off by the naked eye u will be fine some vehicles wheels pull way back.