Back around 2003 I was using the 'frankenmags' that were around back in those days before the Cproducts mags were out in full auto with a registered M16 lower. I wanted more than 30 rounds of fun and wanted to run 75 and 100 round drums. I don't think you can use drums with the LAR-47 so less options with that.
I got a RDIAS and the AR-47 (Michael's Machines) using drums and the occasional 40 round Bulgarian polymer mags and steel Romanian mags. I didn't have to shorten my feed lips at all. I did have to grind on the top of the feed lips for the steel Romanian while the Bulgarian polymers didn't require any touching of the feed lips.
I then switched to the MGI modular lower around 2004 and use the same mags and drums. I primarily run drums and all full auto.
The biggest problem I had back in those days was the bolts breaking. I took this picture probably 10 years ago. I still haven't broken that LMT bolt but did break an extractor.
With more competition these days and better quality, I haven't broken the PSA bolt nor some other ones and I run almost exclusively in full auto.
Video of 75 round drum in full auto using the MGI w/ the AK magwell.
https://www.youtube.com/watch?v=L0HxzM8f8LU
Video of the 40 round Bulgarian mag also using the MGI modular lower w/ the AK magwell
https://www.youtube.com/watch?v=h46zUKXZkNc
I like the MGI lower as a RDIAS owner so I can leave my Geissele SSF in the lower and it is less stuff to drag to the range.
If you want a dedicated setup, the PSA Gen2 KS47 were just released I think this month and worth a look. I'm using their Gen1 KS47 BCG with one of my uppers used with the MGI setup.
On that note, if you go with the PSA, or MGI, they are all standard AR receiver length and you can use the same BCG for both and there are other companies making uppers for AK mags that you can choose from.
This is one such company:
https://www.billetriflesystems.com/