Yes I'm going through this exercise at the moiment, I went away from dropins, actually they werent even considered seriously because of the downsides.
Ive built a pack from CALB 180 Ahr cells, 2P4S for a 360 Ahr battery. But thats the easy bit. Ive got a Wakespeed WS500 reg for a Compass Marine 200A Alt. Again a resonably easy bit. TAO BMS to look after it all, 3 big contactors, 2 x Midnite Kid solar controllers with current shunt charge termination control. I wil be charging my start batt from the old stock alt, so I'll kinda have 2 separate systems. Voltage spikes etc are taken care of