Which lister diesel as a battery charger

Hi all
First time poster here. So be kind.
Apologies if this topic has already been discussed but I can't see any record of it.
I have an off grid workshop that currently has light and power through 1500w solar panels, a 24v battery bank and a 2000w inverter.
I have a 3000kva generator for running compressors etc when needed.
However the great British weather as it is doesn't bring a lot of day light, let alone sunshine at this time of year. I'm therefore looking into obtaining a small stationary engine, not running a genset but an alternator to keep the battery bank topped up when dark / over cast and to power a diesel heater (again through the batteries and inverter).
I believe running a dc alternator to be a lot easier than a genset which requires certain rpm to get the correct frequency.
My research makes me believe a 4hp or so engine would be sufficient to run a 80amp 24v alternator. I need an engine happy to run 24 hours a day, frugal, diesel, low reving and most of all quiet. 🤫
Reading this and other forums I have come to the conclusion that a LT1 or LV1 would do the job. I believe these came with an optional silencer.
4hp at 1500rpm and using around 1 litre per hour.
However I believe a LR1 is a similar size and output.
Any thoughts on which would be best suited, quieter and more efficient?
Thanks in advance.

All these Lister diesels are air-cooled and so not as quiet as a water cooled engine.
They also come in various HP as well, starting as low as 1.5hp, so you need to check the spec when buying.
The LR1 is a nice engine, but you might want to consider a water cooled Lister CS diesel at 5hp, very popular with off-gridders.
Another good small diesel is the Petter PAZ1 but I don't think spares are as plentiful for these as they are for the Listers. Petter AV water cooled 5hp diesel is also good.
Just a few thoughts of little value.

Lister cs is the way to go. The smaller air cooled ones will send you deaf.

Thank you all.
I will look into a CS 3 or 3.5.
Plus I do like the sound of them ticking over at 600 rpm.
What would you think the fuel economy of these would be?