I actually think that it could use a ventral engine cluster, just not one as extreme as in th'initial incarnation. In th'second incarnation, th'bulk provided by th'rear engines look a bit unballanced, like it would tend t'nose-over in normal flight. Include a ventral engine strut, but place it halfway from th'nose t'the tail, rather than near th'nose as in yer first image. Then make it about half as long (or tall an ye prefer) as it was before, an' instead of one large engine, have 2 smaller ones. The ventral engine strut should be wider than 'tis "tall".
For a different take again, use yer original design, but move th'engine strut about 2/3 of th'way t'the back. Then, on th'front end of th'engine strut, in place of th'upper pair of intakes, extend it forward t'about th'point where th'engine strut begins on th'1st incarnation, an' have a fighterbay in place of intakes.
In any case, that space just below th'rear engines looks like it needs something. Perhaps additional engines there could augment th''"fast corvette" image.
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My slighty annoyed compliments to whoever coded this on-the-fly text alteration thing. It seems my post has been "Pirated" by an April fooler.
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