323i coolant system man enough for 325i low compression swap

[Duncmasterflex]

Guys, I'm tearing my hair out trying to wrap my nut around the various set ups and rads for these motors!
My '85 323i has had a 325i engine and box nailed into it by the PO, now it's a low compression engine and has the single outlet water pump, but it's running the original rad ( small) and has just had a t-piece put in to make two pipes run into 1 on the single feed water pipe.
Now the car was stood for 8 years and only run up a few times, so when i recommissioned it i changed oil, coolant, cam belt kit, plugs etc and proceeded to drive it properly. A week later i thought the head gasket had gone (sump full of mayonnaise) but turns out head was cracked.
I've now rebuilt it with new end shells, rings, new polished and ported 885 head etc, so i wanna make sure she's proper.
Will running the current cooling system be an issue? Is that little rad man enough?
Does the water pump modification pose a problem (can't see how it should)
New stat, sensors, viscous clutch also fitted.
Also may cut out the solid slots in front middle grill for more airflow to rad?
Please help guys, I'm so close to getting her back on the road but this coolant worry is cooking my bloody head!!!!

[Duncmasterflex]

Anybody...?

[jimmyspeed]

from the wiki -

Cooling

The coolant system for all M20 engines is pretty much the same, with radiators varying slightly in size but not having any real effect on the quality of the cooling. The one significant difference is the expansion tank. For engines before 1987, this was bolted to the right-hand suspension turret, just in front of the battery. For the 1987 facelift it was relocated to the LH inner wing, just behind the headlight, and the hoses re-arranged accordingly. This difference is clearly visible with the water pumps available for the engines, whose outlets change to suit the plumbing layout.

i'd say if you have bothered to rebuild the entire engine it would be false economy to trust some old unknown radiator/waterpump for the sake of a few quid

[Duncmasterflex]

Yeah I've sourced a replacement rad same as the OE (DENSO new) so i might bomb that water pump off and for a pre- facelift one and be done with it. So as long as the cooling systems are aren't really any different in performance, can't see that a few more horsepower is gonna warrant a much bigger rad ...
Cheers Jimmy, hopefully get some more input from other zone members just to put my neurotic mind at rest....