Wides on 8x10 are more subjective to your subject I think. When theres not a lot of room to back up, a slightly wider lens like the 210mm would come in handy. If you often shoot in situations where this happens (like with your back to a cliff, or on sidewalks or interiors of small rooms) a slightly wider lens is a good thing. If not, then it would be redundant.
OTOH the 240mm and 3005m are awfully close together. IMHO you'd get more variety adding a 355 G Claron, or if you've got budget concerns, go with a 270 G Claron and forego both the 240 and 305.
With your subject, architecture, a 210 G Claron would work nicely, but since you already have a 240, you might look into something like a 165mm f/8 Super Angulon or similar Grandagon if your lensboards will accomodate one. If you're shooting B&W and contact printing a 159 Wolly will work fine, but you'll get more wiggle room with a 165 Super Angulon (if that is a feature you require)
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