hey Adam,
if locking down the font & size etc. doesn't work out as an option, then a replace statement isn't really that bad...the worst part will be just writing a couple dozen repetitive lines and this shouldn't be that resource intensive.
if you have a formula like the following where you're first replace the entire font table with just one font. then you replace any potential f#'s to f0 and then any potential fs#'s to your default.
r:= {your memo field};
r:= replace(r, r[instr(r, '\fonttbl{') to instr(r, '}}')], '\fonttbl{\f0\fnil\fcharset0 Lucida Console;}');
r:= replace(r, '\f1\', '\f0\');
r:= replace(r, '\f2\', '\f0\');
r:= replace(r, '\f3\', '\f0\');
// add a bunch more lines for f4, f5, f6, etc.
r:= replace(r, '\fs16', '\fs8\';
r:= replace(r, '\fs20', '\fs8\';
//etc
you'll need to do the same if to cf#.