conversion

I’ve been massively into bikes for the last 25 years but only now starting to look back into older stuff. Just picked up this Rocky Mountain Hammer this morning and would be keen to hear peoples thoughts on it as there’s not many posts about them. I can’t find any others this colour online...

So I am wanting to try converting an old mountain bike to a gravel bike. Some of my concerns include reach because going to gravel bars from flat will effect handling, and the second big concern is tire size. The two bikes I have to choose from are a 1992 Gary Fisher Sphinx 700c tires or a 1990...