Chad,
Welcome to the Club - you'll get some good advice here.
Your comments indicate you're already headed in a good direction. The standard T panel came out with the 1968 model; from the standpoint of an easy transition, unless you go with full glass, it just makes a lot of sense to stick with a '68 or later airplane.
A common theme here and elsewhere is that it is almost always cheaper to buy an airplane that has the avionics you want than to install what you want after you buy. When you upgrade, you don't get your money back when you sell, so if you are a buyer, take advantage of the depreciation.
I owned an IFR 150 for several years. It had dual navcoms, one with an ILS head, an ADF and encoding altimeter. I flew it IFR with some regularity and it got me where I wanted to go. A handheld GPS with XM weather let me avoid weather and allowed me to request "radar vectors direct" on long legs where following VORs would make for a circuitous routing. (A handheld cannot ever be primary IFR navigation, but if you are cleared direct to some point via radar vectors or an assigned heading until receiving a VOR you can use the GPs as your backup reference. It's perfectly legal.
Looking back, I would like to have had an IFR GPS in the airplane - with prices dropping, you may be able to find a 150 or 152 with a Garmin 430 in the panel; I think that would make for a nice airplane.
Avionics shops tell me that going with the 152 because of the 28 volt system gives you a little better reliability for the electrics - I don't know and someone else here probably has good experience on the subject.
It's almost impossible to find a 150 or 152 with long range tanks, but if you could do so, and if it's equipped for IFR, it could be a heck of an airplane for personal, solo travel.
For my wife and me and a very small amount of baggage, having an IFR 150 meant we were able to make a bunch of nice weekend trips with flights of about two hours that would otherwise have been six hours of driving. So long as there was a good alternate nearby, IFR in a 150 works well. I did push the power up as I did my best to hold at least 100 KTAS when IFR and I plotted and schemed to find the best altitudes for winds as I figured I had about 3.5 hours to dry tanks. That meant a destination I could make in 2 hours with an alternate not more than 30 minutes or so away. I also did everything I could to stay out of ice because a fairly small amount really ruins performance.
But, when you break out on the ILS at 200 and a half and there's some airplanes holding short, you get the strangest looks as you whistle by them before touchdown. It's worth the price of admission.
Warmest regards,
Rick
