Totally maxed out 3.0 piston dome with stock valve sizes ~ 47cc (Ie 3.0RSR piston)
My recommendation: build a 3.0L on an 3.0SC base, and turn up the cams/compression/ports to the specs. you mentioned (basically RSR). You can find cam info on Elgin, Web Cam websites. The 3.0 is just a way better base, for less $$: bulletproof alu case, 9-bolt crank (much better, not a lot heavier), 4-Bearing large base circle cams, and big valve heads. What's not to like.
It is preferable to reduce the head chamber volume as much as possible on the 3.0, for example with some careful work you can get down to ~85cc from 90-91cc on a stock head...this makes a significant difference to your compression ratio. Any much below 80cc on a 3.0 head ( you can get there by filling in the chamber with some aluminum welding, a la IMSA single plug 962 ) you are probably hurting flow and not benefiting from the compression increase any more..
If you are keen on the 'real deal' 2.8 long stroke like you asked about, as opposed to the 3.0,
my recommendation is to use an early sandcast alu case, 2.2-2.7 heads (make sure they *flow*), and all the rest of the specs. basically 2.8RSR. It's a cracking motor. Try to put in some bigger intake valves, like some 48's.
Unless you are in a 2.8L race class and you are routinely spinning 9000 to keep up, forget the 2.8 short stroke, IMHO. OR, unless you are spinning 8k + AND you are using Gruppe B cams
AND you have a K29 out back 
The 2.8 SS, with its tiny stroke, "slow" Rod-length ratio and big head volume, is compression-challenged, unless you use some unreasonably "tight" cams, SO the best way to "fix" that is forced induction. However, with turbos, it's best *not* to spin the motor because they make so much torque at low rpm...so it's kind of a strange beast, this mythical high-revving 2.8 SS Turbo. But that would be cool as F***!
Like that 936 video at Le Mans...
Does that help or just confuse you more..lol sorry