The new front end looks like it will be 190mm.
Your other option is to run the standard F104 front end, which should be less than $20 in parts. It'll add a different feel to the car though, you may or may not like it.
What surface are you running it on? The TRF101W is notorious for having a much softer chassis than any of the other F1 that Tamiya has released in the past.
Actually on further inspection all the aluminium bulkheads and parts etc are the same as the 101W so all I would need is the carbon parts and the small plates that fit on the end of the wishbones which should be far cheaper to convert.