adding my 2c
Its a desirable car, so worth considering all options - think it also comes down to the quality of the car (are we talking concourse with the original sheet metal, running gear and desirable options or more driver)
Obviously to sell, the market is much larger for a LHD car (and now in AU, we can keep them LHD and enjoy - was not always the case) but also remember that with our import costs (LCT/GST etc) bringing in a high $ classic is an expensive exercise - so, locally we end up being a bit of a captive market (small one), I do not pretend to know every boss/shelby sale but my gut is that more circulate locally than actually leave or are imported in AU)
Summary - I would choose the path of least effort - if the RHD conversion is good (can be engineered for rego) then I would roll with that, enjoy the car (and in the background, you could collect the bits needed to reconvert, so if you ever sell the buyer has options). If its dodgy, back to LHD and enjoy
cheers
greg