[C320-list] Battery Bank Upgrade - Which starting battery??

[Alan Goodman]

I am in the midst of upgrading my battery bank following the instructions in the forum archives.  FYI, based upon cost / benefit ($200 each) I installed 2 Interstate SRM-4D lead acid batteries for the house bank providing a combined capacity of 410 Ah.  (I know, they are not a pure deep cycle battery, but readily available without paying huge shipping charges)
I am ready to purchase the dedicated start battery.  I am looking at a Group 24 (11x 6 7/8 x 9 1/2 inch) lead acid rated at 800 CCA and 1000 MCA.  Looking at my Perkins shop manual, the required starting current is 540A.  Does this seem reasonable, or am I reading the spec sheet incorrectly?  Also, assuming 540A is correct, I have been looking for a fuse to install at the battery "+" (Blue Sea MEGA SEA fuse block p/n 5001), but it seems that 300A is the maximum fuse (per Defender Catalog).  I think that this fuse rating would be inadequate, any other suggestions?     Alan;  Hull #67;  Holland MI; launching last week of April or first week of May, weather and ice dependent !!