Potter:
Sounds like your friend has a C85-8 series engine. This is for use without electrics, and are generally fitted on "short" engine mounts.
The C85-12 series is fitted with a different accessory case, equipped for attachment of starter, generator, etc. These components usually require a longer engine mount (and hence different cowls, etc). But some of the small lightweight B&C generators and starters might permit fitting on the short mount. You might also need new mags.
Your friend's first port of call should be to download the Type Certificates from the FAA database, this will give indication of whether the engine would be approved in the USA (and hence can be used as a basis for approval over here).
http://www.airweb.faa.gov/
I think one type can be converted to the other, but obvi ously at some expense. The accessory case would have to be removed and either modified or replaced. Norvic at
www.jadeair.co.uk might help with a quote.
I should suggest that the cheaper method might be a wind generator, but of course Armstrong will still be in demand as his starter motor!