I'd go the XR over the TE50. Most will disagree with me but for ease of sourcing parts, general condition and cost, that red XR8 has it for me.
If V8 is where you're looking I would definitely stick to AU. Too many little issues with BA's both XR and non XR V8 that can add up to big repair bills. I have owned a BOSS engine but would probably not buy another one unless it was covered by warranty, which for obvious reasons it wouldn't be! Windsors are a well proven (over 40 years of use in various forms) reliable engine that are well supported in the aftermarket so parts are easy. Granted the modulars have the edge in terms of power, but there's so many tradeoffs to me it just isn't worth it.
........and you can't beat the sound of a Windsor....
