Those axles will be about 64" mounting surface to mounting surface. The rear you would have to weld on new perches if the stock ones dont align. Also you may have problems with the driveline hitting the stock gas tank because the quadratrac axles are offset to the pass side. I am not sure but I think on the 76 the front diff is on the pass side. This would require a new t-case or to swap the tubes around which is definatly not worth it, just get another axle or a later model. For the front you would need to make leaf spring mounts or you may want to use the coils. I am not sure about the coil spacing if it would be enough. You would also have to make alot of brackets on the axle and on the frame for the locating links. Also do a search in the conversions forum for solid axle swap, you will get alot of info there. IMO it would be alot easier to make a bronco axle work if you retain the coils. If you choose leaf springs it might work, at least in the front. Good luck with it and I hope this helps.
