Hi Dave,
Congratulations on your purchase agreement! I hope it all works out for you to finalize the deal!
We own a 1984 E30+, hull #637, so five hulls later than your boat--almost siblings!! We have owned her since 2006 and love it--they are great boats if they have been well cared for and in good condition. There is a good book written by Don Casey "Inspecting the Aging Sailboat" which might be a good reference in preparation for your survey (You don't mention if this is your first boat or if you are an experienced sailor with knowledge about boats). I'll assume you have or can get general information about boat surveys and things to check, and restrict my comments to things specific to the E30+.
An important issue is the deck area around the mast step, as these boats were built with a plywood support there but it is generally not adequate and may cause deck gelcoat cracks and/or movement of the compression post supporting the mast. If it hasn't been done previously, it would likely need a metal plate installed above the compression post (open the zipper in the forward part of the salon to inspect this area from underneath) .
The tie rods behind the cushions in the salon were reinforced with epoxy on my boat, so I don't know if that might have previously been a weakness or is specific to my boat. Check for cracking in the fibreglass where the tie rods connect to the hull.
If the ports are leaking, you will see staining or wood rot in the teak around the windows. Leaks there can also be caused by a leak in the bolts securing the traveller mounts--those can be accessed through the zipper below that area.
The aft end of the keel/hull joint tends to separate a bit (about 6 inches in length) on these boats. I don't know if that is due to placement of the keel bolts or some other reason, but I've seen this on a few of these boats. It's not serious in my opinion. Keel bolts should be tightened from time to time when on the hard, and the keel should be rebedded at some point as Ericsons are known for using too little caulk in the keel hull joint at the factory. When we dropped our keel 2 years ago, the bolts looked fine, but the keel dropped down from the boat much too easily, and the caulk layer was thin. If you do have a short crack at the aft end, and there is no leaking into the bilge or weeping from the keel joint at haul out, then adding some caulking to fill that crack is likely sufficient.
Those are the main things that come to mind for the E30+. In general, these are great boats, well-built, lots of fun to sail in a wide range of conditions, and fun to own. Feel free to ask specific questions, especially after your survey depending on what you find, and once you own her.
Frank