Mark,
I am not a CRS owner, but offering some suggestions that may help.
Have you tried contacting AC to see if they will provide drawings of where the tank is housed, or will develop a tank for the car?
I do not see why you should have to dismantle everything ahead of fitting, being relatively modern, dimension details should be available.
Have you approached any fuel tank fabricators?
Have you considered the internal design of the tank, such as baffling and an integrated swirl pot(this may be handy on a fuel injected car).
If you are putting a very powerful engine in, what about foam filling? This for safety and handling.
I did a little digging re: sender units and found something that might be worth looking into (it may be expensive though):
http://www.tek-tanks.com/senders_gauges/digital.html (I know it is for boats, but I think still worth a look).
There are lots of fabricators of tanks, an example here is:
http://www.proalloy.co.uk/cgi-bin/shopwise.pl?id=proalloy I do not know how good their work is, but if you go to a professional car tank builder they will know the implications of what you require.
Another possibility to look at is a fully plastic tank such as:
http://www.imagentaplc.co.uk/fuel.html You probably are going to get set-up costs and there need some commitment to go this route.
I know you want support from fellow owners, but costs and installation details are what people like ahead of committing. Someone always has to do the "leg work" and generally will not get money back for it (praise is always nice to receive); so trying to get estimates etc. might help encourage people to have some input.
You have gone to a good source with Gerry, and if you can get a tank made to suite other marks then you will widen your market - what about approaching some of the kit car makers and see if you can hide costs with them. (I know I should not mention "kit" but they use fuel tanks as well and they must be bespoke).
Ok, nothing concrete here, but hope helps,
Q.
