Welcome to the FISD!
It's always easier to trim than add shims. When you have to shim the seam needs to be filled with ABS paste(a mix of small pcs of armor scraps mixed with acetone) then sanded and polishing. Lots of work. But doable.
I have a set of RT Mod and it definitely will fit you. AM is also another option to look at. Both are great set's.
Good Luck Future Trooper!