I think the HiMass is basically musch the same as a Gotoh. I had a Gotoh originally when I built my fretless precision, but swapped it out as I preferred the punch you get with a BBOT. I did a dry run without drilling (blutak) and tried putting a bridge cover on - it will fit, but the screwholes will need to be between a quarter and half an inch further back than for a BBOT.
With the screwholes in the normal places it definitely won't fit. With the holes moved back, you should easily still have enough room that the front of the bridge doesn't play peek-a-boo out from the front of the cover.