Hello and welcome. Your definately in the right place for advice.
Like others have mentioned, your mainly fixing common faults, and as long as the bodywork and interior is good, your on to a winner.
The only issue would be adding V6 suspension matey. Your car will sit very high on the front as the springs are set to maintain the heavier front axle weight of the V6, and yours isn't.
One tip though: SRi suspension is indentical to GSi suspension (but bear in mind GSi is for V6s only). Plenty of manufacturers offer aftermarket kits though, and you can fit the suspension from any SRi year, as long as its not from a) a diesel or b) a 2.5/2.6V6.
If you've any questions at all, feel free to ask away in the Vectra B technical sections.
P.S. We have quite a few how-to guides too.