Hi,

I think you are asking, should I go large or not!

If the new Sanden does have more displacement, I suggest you go with the larger.
7mm really isn't that much of a difference.

It will give the engine a little more torque advantage over the stopped compressor when the clutch reengages.
The engine will turn more than the compressor will if is larger than the crankshaft pulley.
Any displacement difference will make up for the the lesser speed.

This is good under any residual head pressure, especially on hot traffic days, if the system has not had the chance to equalized somewhat between cycles.

Since this system does not use a TXV but an orifice tube expansion device, you are kinda stuck with its performance with that evaporator. No playing with superheat adjustments to control amount of flood percentage.

The best thing is to make sure the condenser fan is working as it should and the fins on both the condenser and radiator are clear of debris.
You want to get as much of the hot vapor gas to condense to a hot liquid and then lose some of that heat as well!

A steady liquid flow through the device is what is wanted. An orifice device works at a steady pressure and quantity of "designed in perimeter conditions" world wide!
The liquid pound and ounce charge is more crucial without excessive reserve.
Bottom line is, the whole system, "Is far cheaper to make!"
Plus they get away with no thermostat, which is another expense.

The flow amount is like having a bucket of water steadying pouring on a fire instead of several glasses slung (sprayed) by hand per minute!

If done correctly and if the compressor is you get is up to the capacity of the two coils, it should still do a very decent job!

Just don't expect ice cubes or snow flakes to be dispensed!

Phil