I always say fix the RS shell, regardless of condition. At the end of the day it'll be an RS, not a simple 'Escort' with the RS stuff on it.

Consider the insurance when you tell them its got a bigger engine, turbo'd with fuel injection.
Bigger brakes, aftermarket bumpers, bodykit and spoiler, sports seats... then all the mods that'll be fit(samco hoses for example) etc etc.

However if you decide to Bonus it. Then its better news for us that'll still have a S2 in years to come by, the more that get reshelled the more return in investment we'll see when the time comes to sell.