There is no advantage in making an engine interference or not, it is dependent on the the basic parameters of compression ratios and valve lift/timing which determine valve/ piston clearance.

The only thing that saves some US spec engines from being interference types compared to their European cousins is due to the fact the fuel available (in the US) is genarally very low quality, (the minimum you can buy in most places this side of the Atlantic is 95 octane) and the US emmission regulations which encourage the design of large engines of low specific power output, thus requiring the design of "soft" engines for that market.
Most high performance engines have been "intereferance types" for years.

The problem only came to everyone`s notice when some mentally challenged engineer/marketing guru decided it was a good idea to drive the camshaft with a notched "rubber band" which inevitably broke witout warning instead of an expensive (for the manufacturer) chain or gears.

End of rant.

Colin.

1990 740SE B200E/M47, remote C/Locking.