I used to breed himmies and had the same question as you so I called the CFa and asked them. I was told by the CFA that persians and Himmies are actually the same breed and any cross between them is perfectly acceptable. If you breed Himmy to Persian and get a mixed litter they told me to register the colorpionts as Himmies and the non-colorpoints as Persians. My Ninjs Su's (she a Himmy) resistration papers say she is registered as a Himalayan-Persian. She has no "Persian" blood and a full Himalayan pedigree. They should not frown on you in the show hall because the two are one in the same breed. A Himalayan is just a fancy name for a colorpoint persian and actually refers to the coat pattern. Any animal colored like a siamese or himmy is said to have the Himalayan coat pattern. This is a temperature sensitive gene limiting color only to the extremities. My cousin used to breed Himalayan rabbits.
Sorry, got to rambling and prolly told you some things you already knew. But I just wanted to tell you what the CFA told me.