Just my tuppenworth - my recent LS400 purchase was a gamble with a similar background - 4 years storage, low miles.
It had clearly been looked after prior to going into storage - but that wasn't a reassurance against the risk of unforeseen issues - many mentioned on here.
For me, the risk paid off. There was no issue with brakes, engine, electrics or any of the things you might expect to deteriorate. It was like the VW Beetle in Woody Allen's Sleeper - turn of the key, like new. Ok, it needed an alternator and tyres but I could see that and factor them into the price.
I've just done 2500 miles in the past 2 months with no problems - potentially a small coolant leak but nothing to worry about.
If there are ever cars to take a risk on with storage and lack of use, these are.