Probably a daft question Alan, but if they are taper roller races, they
have the slightest amount of slop in the bearing & the end of the crank can be moved up and down *very slightly*
when they are correctly shimmed.
Extracting the outers can be easily achieved with aluminium crankcases by just heating them in a domestic oven. Gas Mark Nine, make yourself a coffee & sit on a kitchen chair to await the "CLANG!" from the oven as they drop out. Done.
Velocettes have TRB's on the mains & many a happy hour I've spent taking hot cases in and out of Hazel's oven in order to add or remove another bloody shim!
If the races are not pitted, shimming is your answer - fiddly, but cheap!
Inners can be a LOT harder to shift, but I'd at least try a thinned cold chisel twixt track and flank. If they are scrap anyway, nothing lost & they may readily move along the mainshaft with little effort. Be prepared to give up though & resort to crueller methods.
Finally, have you priced the new bearing? Bearing prices vary widely & it might be a help to say that many cars use TRB's as wheel bearings & some work poring over parts books at a motor factors might make a big difference to cost.