James,
yes, easy access once the housing is out, but getting the housing out is a lot of work. If you search the Technical info section of the site you may find complete directions, but in short, I think it involves removal of the glovebox, radio, disconnecting the defroster ducts (which is a real chore on the driver's side) and disconnecting the control cable from the heater control assembly. Maybe the tach and speedo, too, but I'm not certain, it's been a couple of years. You can probably do it in a weekend if that's all you do.
At that point you've got the dash mostly gutted, so if the dash wood needs resto, now's the time, as well correcting anything else that needs work under there (heater control bulbs, seals, blower, drain hoses, etc.). Allow a few weekends if you go this route, and the car won't really be drivable.
George Davis
'69 280 SL Euro manual