Proposal number two: don't make any changes to the syntax, but treat
these as *literally* numeric scale factors.
k = kilo = 10**3 M = mega = 10**6 G = giga = 10**9
int_value = 8*M float_value = 8.0*M fraction_value = Fraction(1, 8)*M decimal_value = Decimal("1.2345")*M
This is the only variant I've seen that I would consider "not awful." Of course, this involves no change in the language, but just a module on PyPI.
Of the awful options, a suffix underscore and multiplier (1.1_G) is the least awful. It's a little bit reminiscent of the optional internal underscores being added to literals.