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I think Old Glory would be massively over scale - there is a british manufacturer 'Tumbling Dice' who do a range of actual 1/72 metal figures which are absolutely compatible with plastics and this includes crossbowmen - there is one in their Norman/Breton range which I expect would be most appropriate for the Crusades and a couple in their War of the Roses range which might not match so well. Here is their website
Jason,
Just to continue Graham Korn's suggestion of Tumbling Dice, I have their Viking packs on the way to me now and I'll let you know what I think about them compared to Strelets Vikings.
307. CHAINMAIL CROSSBOWMEN is the set you want I think
Oh and how about the Valdemar set: Mercenary Crossbowmen?
Check out Thunderbolt Mountain's 25 mm Arthurian range. Though somewhat taller than most 1/72 plastic sets, they are much truer to human proportions than most metal sculpts. Unfortunately the crossbowman they offer is probably over-armored (chainmail, helm and quilted gambeson) for the Crusades.