73-87 Chevy truck fuel tanks sizes and swaps??

[MeanYellowZ]

Gonna do work on an 81 2wd shortbed. I will be upgrading to a newer (87 I guess..) fuel tank with the baffling for fuel injection. Will do pump and matching sending unit.

Is there an easy way to identify what size tank the truck has now and am I right to assume that the same size newer tank will bolt back into the same brackets?? Should I just order up new brackets/ straps at the same time and do the whole job?

Who has done what when fuel injection one of these with a newer tank swap??

Thanks guys