You'll be fine with either. Those objective sizes easily fit with plenty of clearance. Here's a Leupold mk2 mount with a 42mm objective scope for reference:
Then the PEPR with a Burris AR556 4.5-14x42 on top:
Those are 1" scope tubes. In the 30mm version, I've fit 56mm objectives in the PEPR mount:
The dimensions leupold gives from the center of the ring to the rail is 1.4" for the 1" mk2 and newer style Mark AR cantilever mount. The PEPR is slightly different at 1.5". The 30mm mount is listed at 1.6". As far as cheek weld, I haven't had an issue with an of the stocks I've had. That includes the PRS, ACS, gunfighter and A2 stock. YMMV on that though..