Replacing radiators...Heat output from an aged floor rad 34in.w x 26in.h x 6in.dp using hose down at 140 F deg? Would like to replace rad next to equiv. amount of baseboard rads...

Would like to replace rad next to equiv. amount of baseboard rads which I believe are typically 150 BTU/ft of length, but don't know required length. Want to use this result to cross-check result obtained from floor-space steam calc---I think its better to replace what we know works a bit than use theoretical calcs that probably don't information for all variables.
Answers:    I would recommend using the proper nouns calculation instead of only just swapping out what you have. The out-of-date systems were usually over sized. These calculation are not theoretical, they are proven if you enter the proper variables. If not done properly after you will have a problem for sure.