It is quite do-able to make converters to allow the FM radio to tune the new FM band without ANY modification to the old FM radio.
Though, it will take significant time and effort to build a converter. I chose to make one out of an old turret TV tuner which lends itself to the task very well.
3 strips will need to be modified to cover the full FM band as the old one is 8 MHz wide while the new one is 20 MHz wide.
Of course, powering the tuner and providing AGC bias as well as proper AFC bias if necessary is another task in and of itself.
Once done, it would provide a converter capable of allowing any pre-war FM radio to tune the new band.
If you collect them (as I do) it is well worth the effort.
Here is a video of mine in operation.http://www.youtube.com/watch?v=p_K41tHhHgM