There is only one really good reproduction dashpad available for both the 300G and H, and it is made by RD Autoline out of Sweden. They are just perfect, and you won't be able to tell it from factory. RD Autoline is easy to work with too, so don't let its Sweden location deter you. Email works very well. It is rare that I am really satisfied with reproduction products, but theirs are just the best.
Check out the discussion on the Forward Look site as well, and see a photo of the 300H dash pad from them that is the same as the 300G except the G pad is black and the H is a golden brown. The detail and definition is clear, and they fit just like they should.
You could get your original pad restored by Just Dashes, but I would rather use an original cracked pad than their restored one, which is really puffy, the lines lace any clear definition and I have seen some where the linyl overlay doesn't stay flat - and they are twice the price of the RD Autoline reproduction new pad. I recently ordered a dashpad for my 1961 New Yorker that is the same as the 300G, but in my case a different color, from RD Autoline (mine is red, and I sent them a sample of my original pad color, and they matched it perfectly). With the special color reproduction, their price for me was $700. Shipping was also much more reasonable than I ever expected too.
The RD Autoline website is: