Brian,
Thank you for your comment. I have the same fill neck/cap in my upper radiator hose. I also agree about mounting the expansion tank between the Radiator and the water pump. I have plenty of space in that area and I am TIG welding a brace that runs between the the left and right control arm towers and this will be the perfect location for mounting the expansion tank and my remote
oil filter assembly. Easy to get to and also looks good.
I am thinking of purchasing a Canton Racing 80-203 and mounting in that area.