I read your posts and am equally disappointed with your final results. My .02 says to look around for a used refurbed coal stoker boiler, and hook it up with the oil boiler. The chimney issue is controlled by adding a power vented device (if necessary) for the oil boiler, and the coal boiler will solve the heating issue. I'd definitely consider a larger than mentioned boiler and enjoy the comfort, with not worrying about the heat loss. Sure, you can add insulation, replace the windows, doors, but if you continue with the oil and do that, the payback will be slower, and comfort level slower to achieve. I don't recall where you are, but ask more questions; do more research, and stay the hell away from the 95 to 98% efficiency boilers.
Slick presentations don't do a damned thing in the real world, AND those boilers aren't designed to last 50 years. They will be obsolete in two years as "The Next Big Thing" gets introduced. Do NOT ask the guys who sell them, ask the folks who have owned one for a while. The 'Keep it Simple Stupid' guys lose out to the techno guys. If you are a lab rat or a bean counter, go for it...........good luck!
You need a K-8, EFM 700, LL 220, AA 260, AHS 260, Van Wert 600 or 800. PM me if you want to have some more free advice. For the price of the coal stoker installed, you could not even replace the windows on the first floor, let alone the insulation...... As for your wife outlasting you, that is very funny......hell, you'll probably live to be 105!!!! Take care of your heart, it is not easily exchanged......or cheap.
I've done it for 44 years and seen lots of folks get screwed over for no reason other than they did or would not listen.