You won’t do much better than this 30page long thread on MEM forum. Starts of with Graham Corry talking about a build and goes onto my build and a few others along th eway. You wil need to register to see some of the images which have been posted as attachments.
https://www.modelenginemaker.com/index.php?topic=7440.0
Also if you have any questions, join the Alyn Facebook group where Graham or other members can help. He can also provide drawings and the couple of pages of notes if you are missing those, just let him know the engine number for the castings you have
https://www.facebook.com/groups/ALYNFOUNDRYMODELS/