We got a lot of parts off the Air Weapons Range in Cold Lake Alberta when we were restoring a Sherman 10 years ago. Even found 2 Skank Turrets with out a scratch on them. Air weapons ranges seem to have better parts than Anti Armour Ranges. Fewer hits and more training ordanance.
Still, to find serviceable road wheels and trank for a Crusader would take a lot of luck. Why British armour any way? Othere than Centurians and Ferrets there isn't much British stuff on this side of the pond to work with. Better to chose something that you might be able to find lots of parts for.
If domestic familiarity is the key, then I cannot lie, other than a T 55,
I would choose a Cyrstler powered M4 Sherman, I have seen about half a dozen scattered throughout the country in various muesums and even one restored in drivable condition, powered with an old Cyrstler radial in it (back when they made good engines).
I know a TON of resources and places to go if I had questions about general topics on the M4, even a few reference tanks to look for cosmetic details, and to make it appear in war era coloration.
Another advantage hosted by the Sherman is so many countries used it, you can really go far in terms of what nation would you be restoring it under ( Example, if you could find the parts, you could make a Canadian, or even IDF Sherman).
Cool stuff, all you have to do is have it certified under state and federal law, the obivious being disabled weapons, other than that, having working lights, turret, and beatifully restored suspesnion and transmission, and you can really ruin someone's lawn hehe
Cool thing about a restored working tank, is unlike say a classic Pony car... you just kinda wanna get it filthy.