The focus issues only become apparent at f-stops less than 2.0 thanks to DOF hiding the problem. Thus the Jupiter 8 & Industar 61 don't exhibit the problem. Since your I-61 is from a Fed 5, it's more than probably a I-61 L/D (the best version of the lens, IMHO, of course.) It's a marvellous Tessar type design and with the recalculation and coatings the FSU used it really is almost too sharp in many circumstances. Give it a good workout on the kinds of things you like to shoot and make sure the results are what you want - looks wise anyway 😀 A good Jupiter 8 is an exquisite lens as well, so give it some consideration.
Hope this helps,
William