....and 74 is nice and early, so hopefully better structurally than some of the later ones (I know it varies). Interior is likely to have considerable sun damage if parked outside, there may also be chassis leg rot etc, I'd say underneath was as, if not more, important than the panels at this stage.
Check for sill rot, corners of boot by the arches, front edge of rear wheel arches, chassis legs, especially under the battery and around the subframe mounts, see if it has been ziebarted or waxoyled that may have helped. Look out for cover sills.
There are various picture threads on here about chassis repairs including chassis leg replacement if it needs them and pretty much every area underneath is relatively easy to weld. The club do several good panels - members only - for the commonly prone areas (details in the club magazine or club members area of this forum)
There are some areas of the body which will be more fiddly than others, check around the rear vent panel as that is hard to weld, replacement s/h doors, bonnets and boot lids are all easy to obtain. Wings less so, but the club does 2 good repair panels for them, second hand ones vary in quality (as they are prone to going there anyway)
Engines, Gearboxes, Props are available easily, If you need to rebuild an engine the parts are generally available to rebuild them.
If you have the space and are handy with a welding torch then there is an awful lot to accomplish....
As Dave says....a few pics would be good
