I'm figuring that 70 must be a styled model, and not a Hart-Parr 70. The Hart-Parr 70 has a cast iron radiator shell with the words Hart-Parr and Oliver cast into it, while the styled is steel. Sheet metal is available for both.
Last I knew, Steiners had the 4 piece side panel set for a styled 70 priced at $385. I'm sure you could buy just the front 2 for less, and that Lynch's would be somewhere close in price. You can visit Steiners at <!-- w --><a class="postlink" href="http://www.steinertractor.com">www.steinertractor.com</a><!-- w --> 

I don't know of anybody making reproduction grille halves for the 70 (the 60 used the same ones), but there were a LOT of these tractors made, so it shouldn't be too hard to find a decent set.

Welcome aboard.