Disclaimer: Not a Guru. Also not a psychic! Without knowing more as to the specific gun, the psuedo-psychic in me suggests best maintaining nearest configuration to rifle original, whatever securing screws/pattern presently utilized. That's probably the safest answer if yet largely guesswork. Perhaps to share exactly what you have; full description including model and serial range. Such possibly for an expert to weigh in. IF the screw size & spacing are same between old & new, yet further question of magazine height
Fundamentally, you will need bottom metal with exactly the same screw holes placement. Just now, yours factory designed as appropriate, economic and convenient for the rifle presently configured. Such as your magazine depth & mag spring; possibly both its design and even trigger positioning in trigger guard. and spring may also require modification/replacement. Flying in the blind here, simply conjuring. IF you are featuring something of create opening and inlet according to new bottom metal in hand... Might not work! I suppose that's what you're here about. But experience may be slim. However, the bright side, maybe, deed done, you can be the Guru & teacher!
Best & Good Luck & Stay Safe!
Issues both of 'fitment' as well as duplicating what Winchester deemed appropriate for fasteners.
