The plans are excellent. Here are a couple of photos of my first press, totally home made except for the bearings and the phenolic resin press bed, it's much smaller than yours but the results are very good according to my wife. (She's the artist, I'm the artisan and general assistant.) I've learnt some things along the way so I'm all fired up to build one even better!
The rollers are 46cm wide and about 6 cm in diameter. The press bed itself is 46 cm wide by 70 cm long so it easily accommodates A3 paper. The small size of the rollers, especially the bottom roller, means that you can use a direct drive rather that gearing or chain drive; ours is direct drive to the bottom roller and it works really well. Having said that, it's all in your plans - you just scale them to fit what you want, what materials you can get and what your workshop will accommodate. I don't know what it's like in your country, but here in England the bearings are ridiculously cheap so long as you don't want high speed ones, which we don't, so it's not worth making your own housings or anything, however the take-up bearings I used came in a fairly standard carrier with a larger slot than the 8mm steel I used for the uprights so I had to fit some gib strips (is this an international or an English expression?) If you think it would be useful I'll send you some pics with a ruler on them so you can judge the scale. ( Do you still use proper inches over there or have you been "metricated"?)
It might interest constructors in England to know that my total cost (excluding effort!) was in the region of £120 of which £40 was for the phenolic resin press bed.
thought of something else that might be helpful to builders of smaller presses. I've attached a photo showing the take-up bearings raised to lift the top roller and you can see where I had to cut out the side plate and bottom bearing housing to allow the small diameter rollers to come closer together (arrowed on photo). For the same reason the press bed is thicker, and more expensive, than would otherwise be needed. The other thing I had to do was mount the bearings on the outside de of the side plate rather than inside, but it's only one more hole and some serious effort with a big file!