The thing is, there is no one true razor. Different sources have different associated reference machines - some are more like Turing Machines, others are more like CA. If what you are looking at is barcodes, then short ones are pretty rare - and if you go into simulated worlds, sources can have practically any distribution you care to mention.

Yes, you can model these as "complier overhead" constants - which represent the "cost" of simulating one reference machine in another - but that is just another way of saying you have to unlearn the Solomonoff prior and use another one - which is more appropriate for your source.

You can still do that, whatever your reference machine is - provided it is computationally universal - and doesn't have too much "faith".