the size of shot ....in a shotshell is irrelevent....
if the onces of shot are the same ( 1 1/8 oz as you say )
and they are both loaded to 3 dram ....of identical powder ...
They should be identical ...in terms of velocity and recoil ...
...... but maybe you should ask the guy that made them up for you ( when you ask for a certificate of insurance for his Commerical General Liability insurance policy - as an ammo mfg for sale..) ...hopefully before you pull the trigger on this gun....
I'm not convinced you understand how dangerous this old gun might be ....!! ..unless it has been thoroughly checked by a competent gunsmith...
....but its a free country / and its your hands and eyes behind that gun, not mine. Good luck to you ... / none of us, who urged you to use caution - want to see you get hurt ...but we were serious when we said be careful ....