You shouldn't have a problem the O2 sensors are easy to get to.
Before you drop it in, check your header clearance along the pass. frame rail, i had to do some grinding to the top lip.
I've installed the hotside twice now with the motor installed. I've found the higher hard top motor mounts allowed for a better overall fit over the lower convertible mounts on my particular car. My downpipe slid in much easier and the crossover pipe and charge pipe have more room.
1991 Mustang LX - 306, Ported Holley Systemax, 11R 190 heads, FTI cam, 70mm TB, On3 Turbo kit w/67mm BB .96a/r, PT 46mm WG, MSD6AL-2. Freddy Brown Built FMVB AOD w/brake, 3K stall. 3.27's