I have built 284's on short Model 70's, with the spacer removed (not bad), Sako 579 with a homemade box (worked but not great), Turkish Mauser (good length, fed great), and a pre-64 Model 70. I also had a factory SA Ruger 284. If that rifle had been a 7-08, it would have been a great rifle but this pre-dated the 7mm-08 by several years. I built a few single shot target rifles (40x, Savage 112V, Musgrave) and the cartridge worked fairly well in that venue (this was back when the 162 Hornady was the high BC bullet) but had limitations.
The OP is looking for a longer 7-08 so he can turn it into a 284. I would go with the Model 70 just because I like them better than Tikkas. I don't really like the concept though, because I don't really like the cartridge. GD
