A Jensen 55 is certainly one of my absolute favorites, with their smooth distribution of power, so I'm with Nick & Jim on this one. Keep it original as it is already a classic and destined to join the ranks of riveted boiler engines by the time you reach my age!
Heaters typically don't just up and die, but sometimes connections do, so be sure to have a good look around for what actually went wrong before you throw the baby out with the bathwater!?!?