Well if the OEM converter cooked the previous batteries then it was probably due for replacement/upgrade......so this may be a blessing in disguise. I think that Progressive Dynamics does have a 55 amp replacement for older converters, but I am not sure if replaces yours specifically or not; nor do I know if it is suitable for AGM or Lithium batteries since I use one for my cheap and dirty wet cell batteries.....going on 7 years now on the original Harris coach batteries (but I don’t boondock very often though). You could try calling PD and see what they say:
https://www.progressivedyn.com/rv/po...r-4600-series/
After reading your original situation again it seems that the hydraulic slide was the final straw for the converter. Many basic converters have an in line re-settable 50 amp breaker in series (or what is appropriate for the converter used) between the converter DC output and the coach batteries.......so you would think if you were drawing more current during the slide event, than the converter could supply, the breaker would have tripped before the converter burned up. Of course an old converter may have had its own issues that caused it to fail; maybe combined with hydraulics that may also be drawing more than they normally would when new (binding; lube; misalignment; motor winding short, etc).
I normally always suggest device replacements that comply with original design to err on the side of safety. If it all worked at one time with a 55 amp converter.....it should continue to do so if the failure cause is resolved. You sound like you have a plan in mind for upgrading the charging system overall so I will leave that one for you to resolve. I hope it works out for you and you get your systems running again. It is a good challenge to keep older coaches running safely and reliably.