Results of the test ...

output freq is exactly that expected ... and that MPSIM shows ....

111.1 Khz with a 8 Mhz Xtal
277.7 Khz with a 20 Mhz Xtal

sooo ... getting 1 Mhz output looks a bit too much !!! - gives 72 Mhz @ Clock - 18Mhz Xtal and PLL x 4 ; that looks real hard overclocking for such chips ...
MAY BE POSSIBLE, but with very light loads on the output ...

Alain