First of all, fgf's NEVER came with snaps mounted to the chrome surround trim. If your car has those, I'd reccommend scrapping those as fast as you can and putting the correct trim on. the factory style clips work just fine. Then as 69 Bird mentioned, lay the boot out in the sun for a while. Over time, the boot will stretch out some. The last thing you want is a loose fitting boot, believe me! If you try to install a stock clipped boot over the top of some snaps someone mounted, you will likely tear the boot or at a minimum it will wear at the clips.
I used to be indecisive. Now I'm not sure. I feel like I am diagonally parked in a parallel universe. 1968 400 convertible (Scarlet) 1976 T/A - 455 LE (No Burt) 1976 T/A New baby, starting full restoration. 1968 350 - 4 speed 'vert - 400 clone (the Beast!) 1968 350 convertible - Wife's car now- 400 clone (Aleutian Blue) (Blue Angel) 2008 Durango - DD 2008 GXP - New one from NH is AWESOME! 2017 Durango Citadel - Modern is nice! HEMI is amazing! 1998 Silverado Z71 - Father-daughter project 1968 400 coupe - R/A clone (Blue Pearl) (sold) 1967 326 convertible - Sold 1980 T/A SE Bandit - Sold