Quote:

I was thinking square 4.375 x 4.375

I am sure it can be done, but...

Things get marginal IMO.
B1 head valve layout and piston valve relief with compression height and ring pack location.
More stroke likes a longer rod, to avoid pulling the piston out the bottom of the cylinder at BDC, but uses even less piston CH. So the piston ring pack design will be the part that needs the most work, but calculate all the others (clearing the piston to crank counterweights).