1275 metro engine transplant

[Tarkatom]

I'm currently in the process of transplanting a 1275 engine from a D reg metro into my mini mayfair. To my knowledge this is a fairly simple process. I know that i will need to drill a hole in the top of the head to attach the heater to.
Does anyone know of anything elsee that is required to allow this engine to fit into my mini. I noticed the mountings are different, anyone got any knowledge they would like to share? This would help me no end, thanks.