I checked the Lens Vademecum for you. This is what I found:
'Xpres f4.5
This was typically made in 3.0, 4.75, 5.5, 6.0, 6.5, 7.0, 7.25, 8.5, 10, 12, 16.5, 21in.in the 1920's. Q15 design. It was the major product from the Xpres series and is quite easy to find today. The 6in was suggested for 5x4 and the 3.0, 4.75, 5.5 6.0, 6.5, and 7.0in were in helical focusing mounts if required.
Coverages of 8,5 inch is listed as 7x5in - so you should be okay there with your reducing back.
The f4.5 Xpres was similar to the Tessar previously produced but seems not to be identical to it, the external curves being different in ratio. Thus it must rank with the many me-too lenses then introduced. They were a quality item, covered a good angle, were popular with professionals and are still fully usable today.'
Am not sure about the other lens. If it is a wide angle, I can't find it in the LVM with a 4.5 aperture and only with a 8.25 inch. This is what is said about the pre-WW2 Wide Angle Xpres:
'About 1928 a new Xpres lens was issued, perhaps primarily designed for aerial survey work but available to all. It was the Wide Angle Xpres, roughly of Q20 type but not separable. It was a very high quality lens but a heavy one. (see B.J.A. 1929, p358, p9advert.'new'). The B.J.A. noted the advantage of an f4 lens as a wide angle for focusing. And the 80° coverage and freedom from distortion were praised. It was sold in 7-14in at first, later as:
4.0, 5.0, 6.0, 7.0in for 7x7 or 8x5in, 8.25in for 9x7in, 10in for 10x8in, 12in for 12x10in, 14in for 15x12in, 20in for 22x18in. It had an aperture of f4.0, and covered 80°.
If you have a post-WW2 Xpres lens, the following is said about them:
An early peacetime list (May 1946) is as follows:
Xpres f4.5 3.5-14in for 58° Coated. (The actual foci were 89, 111, 137, 140,
152, 184, 216, 254, 305, 356mm) This was the first item to be sold coated and those seen have a hard long lived coat. (B.J.A. 1947, p3) Note above that the extenal curves show the design seemed to be slightly new also. It has been seen as 6in f4.5 at No 202,31x and also at No9,80x- an example of "anomalous" numbering. Size and coverage of the 8,5 inch is listed:
216mm 8.5in 7x5in £27.60
The 6 and 8.5in lenses are quite common in coated form and usually in good order as the coating was hard: they still are useful to large format users as they are sharp and of good contrast.'
We own and use several Ross lenses and are pretty happy with the results. They really need to be very clean as they are prone to flare. Using a compendium will greatly improve performance. Angle of view is moderate. The wide angle version should give you some more room for movements if it is indeed a wide angle. Mounting them on your camera will tell you soon enough which is which.
Congratulations on your new camera. Have fun using it!
Norm
