Full River HC64L 750CCA in a 380? Possible??

[SH00T]

My 380 struggles terribly with a poor battery..
Throws odd CEL's, though I've never had the Crank Angle sensor issue..
Usually Upper Manifold Abosute pressure
Mass air flow sensor ( recently )
and just now a O2 sensor issue ( Pending ) what that is...

None of these have ever thrown the car into limp mode...
I actually Rang Mitsubishi for a CCA rating and they said 560 CCA.. Yonks ago..
But the general go is 600 or more around here..

I ran an exide as my replacement, 560CCA, ran great for a couple of years and died... CEL's and lacking power, noticably...

Next battery was Century High performance (620CCA), 67EF, I think, same as Red Valdez.... and its time has come too..

I charged it last night with a CteK MXS10 and it reported under 80%, threw it on the charger again, sub 80% again..
Its chuggedy in the trans, poor idle on start, And throws CEL's one after the other, I an chage the battery, clear the faults and it fine for a trip or two, then all over again..

So I found a Fullriver HC 64, , its as high as the Century and Exide, but its over all length is 7mm longer than recommended... Will it fit? Thats the question... At a leisurely 750CCA and a battery I'm happy with the TW ( HC65 - 825 CCA, tight Fit that one ) its been way better than the yellow top.. and very strong in the drain department...

Any else run it?

Just on the CEL thing, I only run one amp in the 380, efficient D class, but about 900 watts.. Never cranked either.. I've heard things connected can set off the ECU like Steering wheel control adapters, Now disconnected, Park light sensing LED DRL's.. ( Full Power when running, Parker mode with external lamps lit ).. All disconnected. Made no difference whatsoever....

But these CCA ratings are for -18 deg.. they are 10-20% over that in Qld Temps.... Doesnt make sense...
Is the wiring to the ECU undersized or something... Beats me...