This is a long term "potential" project
Dave Degans does a "Rolling Chassis" Norton Featherbed kit for £3,500 all in - they can supply mounting brackets for a Sportster engine ( I'll need a complete unit, running preferably) lets say £1500 - so for £5k I have the knockings of a great long term project
http://dresda.co.uk/parts.asp?filter=rolling
Or, the cheaper option is to buy one of these kits
https://www.caferacerkits.co.uk/news/2016/10/23/crk-triumph-cafe-racer for 2k and a Triumph Sprint (Available for around a grand) so - £3k plus paint and services required for the Triumph or £5k plus paint and services for the Norley........
The Triumph is the much cheaper option - may cut my teeth on one of those, then build a Norley.....