RS 232 cable pin out for Uplink 4500EZ and connector type.

Yes and no with the Uplink units and what data they use.
Depending on the area and programming settings, the Uplink units will go for a 4G service first and keep going for the 4G service, even if marginal, before going to a lesser data service that has better signal levels. I don't have the exact verbage on the dealer side handy, but the first 4G units I put in, I was supervising the entire path on the data side and I started getting random alarms and alerts on the accounts. Many phone calls and hours later, that's what between the carrier and Uplink was determined to be the "most likely" scenario.
Without doing hard calcs and factoring in the normal 20% safety factor (120% loaded) I'd use a 7aH battery and call it a day (rough values off 500 mA draw).
Between a LBC, supply, transformer, battery, less enclosure, it's a $50 cost to a sub $200 cell. The 2500's are/were being blown out at around $100-125 for quite some time (last time I really looked hard at the prices).