700x45 isn't a 29er anyway
Here I am.
on queue as always!
The problem here is most 29er's outside tyre diameter is actually less than 29 inches.Take the tyre credited with starting the modern 29er movement, the WTB 700x52c Nanoraptor.
A 622mm diameter rim plus two 52mm tyre sections gives an outside diameter of 726mm or 28.5826771653852 inches. Or 28.58 when rounded down.
So "the first real 29er tyre did not measure 29 inches it was just closer to 29" than to 28".
To get a true 29er wheel you need 700c rim and a tyre that has at least a 59.5mm wide cross-section.
On the subject of 700x47c wheeled Cleland and Highpaths they are incredibly rare with only about five ever made. They date from 1982-1992 and were either prototypes or one off bikes made at the request of a customer. I do believe that there were also some 700x47c cycle speedway bikes made in the early eighties.
As for a retro 700c bike your best bet is to find a 700c Hybrid bike with good tyre clearances so that it can be converted to off road duties. These bikes first appeared around 1985. Most manufacturers made a version. They were sometimes referred to as CityBikes. If you want pre-retro 650b, you might be able to track down an old Finish Army bike. They were heavy and made to last and were fitted with 650b x 54 tyres. They are still being manufactured today.
9/16" Suntour BMX MP-1000 pedals / 56 tooth TA 6-bolt chainring.(I'm not bothered if the teeth are worn or damaged)