radiator issue

[gramps77]

Just installed this http://www.autozone.com/autozone/par...3032_4648_5281
to replace the original in my 77 350 4 barrel AC truck. It is obviously a little larger and doesnt fit perfectly in the lower radiator bracket which then caused me to have to not fully install the upper mount plate cause I could only get 3 bolts in at an angle. I see that there are small block and big block rubber isolators or spacers available. Did I get the big block radiator without knowing and possibly just need to now get the big block spacers to make it fit?
by spacers I was talking about these http://www.ebay.com/itm/CHEVY-GMC-Tr...item53e9a626a3