A word of warning on that 6m mileage. 6m motors are hacked from the original Crown sedans in Japan and sold over here quite literally "by the pound" in large containers chock full of used Japanese engines. The importers advertise 35K to 40K miles only because thats the average mileage of ALL salvage vehicles chopped up in Japan. They have absolutely no way to know the mileage on any particular engine. 6ms have been out of production for over 15 years so you have to realize that these engines have either been sitting around with seals deteriorating and cylinders rusting for a long, long time OR they have quite a lot more than the average 40K miles on them. In our group's collective experience, buying these used motors is kind of a crap shoot anyway, certainly worth no more than a well maintained original 5m with verifiable mileage. As to value, you should disregard anything the owner says about the motor or mileage and base your judgement entirely on condition. Is the paint still glossy? Is the material intact? How's it run and drive? Ultimately, are you going to be happy with your purchase? Value can be grossly different by region and its impossible for us to judge specifically without seeing the car ourselves, but I agree with the previous posts that ballpark an AVERAGE condition mk2, (meaning faded but intact paint, a few door dings, worn but intact drivers seat, squeaks and rattles, 1/8" tread left, no rust in the quarters mabe a small speck on the hatch), in the $2000 to $3000 range. HTH.
Phil D.