Ah, I've said it before and I'll say it again - that's a marvellously executed 6542 build. Didn't make the connection to here when it just mysteriously started appearing in the daily wrist threads
There's a risk of missing out on some great pieces if you just judge them by their diameter (and compare to eg Panerais). Wrist presence is not measured in mm.
Start with a 3646 model from River. With that, you can later update dial hands crystal movement and try reshaping/aging etc. Silix is a cheaper option - and there are many more expensive ones...
Would also recommend you creating an account on homageforum, there is very much knowledge gathered there about vintage Panerai.