The only way to know for sure is to sit in one. Someone on the field, a dealership or maybe someone here can help. I am not yet a Mooney pilot (I'm working on that!), but I have sat left seat in a number of them now and have flown right seat in others. I also have nearly 200 hours in an Arrow IV. IMO, if you feel cramped in an Arrow, it will only be worse in the Mooney. Technically, I think the cabin width on both is maybe only an inch or so off, but the roof curves in tighter and there definately less footwell space. Also in the older F model, the panel is closer to you and all these things add up to create a more clausterphobic feeling. Also I find getting in and out of the Mooney a bit tougher. Having said all that, you will fit and it's ergonomically pretty decent. Only you can decide if you can adjust. The tighter cabin is one of the trade offs for all that awsome speed and thrifty fuel burn. Pretty much if you want a big cabin and anything close to the speed of a 201, you'll need to look at a Cirrus SR-20 and that plane comes with it's own limitations and price tag.