Jack,
There are certainly many picures of TR- Engined Plus 4s running Strombergs with no air filter whatsoever and the reason that the Plus 4 Supersports had the bonnet scuttle was to accomodate ram ends on the Webers.
I don't know if a set up like 40 or 45 DCOE Webers on a swan- neck manifold would fit but others on the site may have more info
Don't even think about pancakes- they just won't fit
One good place to start might be someone like Racetorations who are TR specialists
If you want to go down the bonnet scuttle route, try Malvern Sheet Metal. They will make you a scuttle half bonnet ( price I think about £470-ish in Alu)
Cheers,
G
