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Looking at the shop manuals for the Sprint 2002 - 2004 models and the Sprint 2005 - on models, the later (1050) engine has smaller, by 6 mm crankshaft big end journals. This makes sense, instead of making a whole new crankshaft (expensive) Triumph just offset ground the journals to gain the relatively modest additional 9.1 mm of stroke (from 65 to 74.1). This is a common performance modification that was often used when rebuilding motors for hot rods. It isn't so common now, at least for American performance engines, because true stroker cranks are readily available. The bottom line is that the only clearance issues will be with the big ends of the rods and that should be minor. A quick way to tell would be to compare your existing liners to a 955 liner. Typically liners extend quite a bit below the lower limit of the stroke so grinding a little clearance isn't an issue.
Speaking of liner modifications, there is an opportunity for some free horsepower. At the upper end of the RPM range, the air trapped under the descending piston presents measurable resistance, the so-called "pumping losses". More recent engine designs frequently have semi-circular reliefs machined into bottom edges of the liners between each cylinder so that air under the descending pistons can easily migrate to the area under the adjacent ascending pistons. If you look at a picture of the engine internals of the 2008 Hayabusa, I believe most of the magazines showed this. This is a cheap and simple mod that any competent machine shop could do.
Any other parts you are replacing for which you can get exact dimensions, you might consider using an alternative part from a racing supplier as opposed to the OEM part from your Triumph dealer. A race part is certain to be manufactured to a far higher standard and often will have a performance advantage that isn't obvious. For example, Ferrea supplies valves that are back cut and swirl polished at no additional cost, which increases flow at low valve lift thereby broadening the power curve. I haven't looked through their catalog for valves to fit the Triumph head, but I know you can buy their valves for a small-block Chevy cheaper than you can buy a valve from your friendly Chevy dealer.
It does take a little work to find a part that fits and I guess you have to be a little adventurous, but the payoff is usually there for those that persevere.
Just a thought.
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