Don't let them steer you away from this idea, mz. Steel bikes are not generally flexy or mushy. It depends what bike, what condition, your capabilities, etc. A lot of flex comes from wheels, anyway, and they will be modern. I almost did the same thing with my Wojcik but decided to sell it to a collector and buy the Felt instead. I couldn't deal with wrecking an irreplaceable custom bike in a race.

P.S. Sorry to hear about your grandmother.