Howard,
First of all if IM is building your car then, from what I've seen of other IM's, the $ky is the limit. I don't know if Henry did all the work such as steering wheels, switches (There is a place on Samba that does concours quality dash and gear shiftknobs), emblems (Stoddards or Klasse 356), over-riders on the bumpers, etc... but if he can, I'd have him do as much of it as possible, emblems can be a bitch to put on correctly. My experience with steering wheels is this: Since my car was already built it had a wheel that was crap. So I decided on a Grant that had a "Nardi look", which was followed by a Banjo from Flat 4. I ended up going back to the Grant for three reasons, one - it was a smaller diameter, two - I wanted a Carrera GS look and three - the adapter was billet so it looked more "original". The reason I didn't do a Nardi was the diameter and the Derringtons were too expensive for me. Turnsignal switches have been a bit of a hassle as well. I have gone through two (one broke). I used 67-68 VW Bus switches and getting them so the housing diameter is the right size for the column can be difficult when using Samba or ebay because most people selling them don't have a clue if it will fit your car, they only know which VW it fits. I get the feeling that you are going for an "original look", so I would either get, or have installed, or purchase and have IM install, as much original Porsche items as possible. The original Speedster steering wheels pop up on ebay occasionally - $$$! I've had my hands on all the wheels you mentioned and with the exception of the Banjo they were all very nice, it would come down to preference. As far as original look, that will depend on the car you are trying to create. (I recommend looking over old photos to find the exact car you want and copy it to a tee) Banjos were on the earlier 356's and not on the 1956 and up, at least not as stock. And you're right, it is a very sexual/sensual thing - no matter what, if it doesn't feel good you're not going to enjoy yourself.