Sizing help

My boiler died, and I'm getting quotes for a replacement.

My existing radiators have 343 sq. ft. of EDR. I consulted the old manuals directly, so I'm pretty confident in that number.

At one point, we considered adding radiators back to one or two rooms that previously had them. I think we'd probably have slightly more even heat distribution if we added them back, but it's been fine without them. (I have no idea when or why they were removed.) Referencing the indentations on the floor where I assume the feet used to be, I estimated an additional 80 sq ft of EDR in total for the missing radiators. The odds that we ever add them back is pretty low, but not zero.

We have a 60-gallon indirect water heater and two teenagers.

Most of the piping in the basement is wrapped with 1" insulation, but the elbows and other connections are not insulated. There are also some pipes in a crawlspace that are not insulated, partly because of access issues and partly because there are water lines in there that I think deserve a little heat.

I know I could insulate better. I did what's there myself, which is why the more complicated stuff isn't wrapped. I actually got a quote earlier this year to finish the job, but the cost seemed very high for the expected payoff. I might have the contractor insulate the new near boiler piping and tackle the rest of the gaps myself.

The Peerless 63-03 is rated for 308 net sq. ft. of steam , 63-04L for 383, and 63-x-04 for 388. US Boiler's STMX125 is 321, IN5PVNI is 363, and STMX150 is 388. Weil-McLain's EG-40 is 321 and EG-45 is 388. There are probably other options too. Of course, I'll have to work with what's available and what the contractor likes to work with.

I'm between sizes, and that's just taking into consideration my radiators. Factor in the indirect water heater that isn't going anywhere, the missing insulation that could be fixed, and the missing radiators that may or may not reappear, and I'm not sure what I should do about sizing.

Suggestions?