Most importantly, you're interested in whether the top is held down tight onto the body to seal out water, etc. A thought that comes to mind is to lay a few sheets of printer paper over the area the top contacts, then install the top over them. Obviously, they should be held firmly in place and resist your trying to pull them out. If that works, the gap at the rear isn't important; you've got a good seal to the body.
'97 SL500, 40th anniversary edition
'04 Olds Bravada (SWMBO's)
'06 Lexus ES330
'89 560SL (sold)
SL--Anything else is just a Mercedes.
(Kudos to whoever said it first)