Looking at the design of the plate I’m guessing early to mid 80’s. there will probably be a date stamped into the outsid edge of the flywheel if you pop the airshroud off.
Edit I’ve just relooked at the photo and its got an early type sump fitted which makes the engine 1950’s. a bit of parts swapping maybe?

Just noticed your new avatar, I had to blow it up because I thought I was seeing things with my new eye I got from the hospital last week.

What type of bird is it, I can’t find it in any of my bird books 🙂

Phil

Just found it in the book, it’s a “cocker sparrow”