Thanks! but i think 169741 is for gen V and VI. The Merlin 540 shortblock is a mk IV, Right? But I can´t find the #139741 that should be the mk IV cam.. Maby NLA?

Sorry...you are correct...didnt see the gen model that you were looking for...but yes...the 168741 cam is for a Gen5/6 motor. The 139741 cam is no longer made and was replaced with the 139021. The one just under it is 139011 and these 2 cams (139011 & 139021) are for a NK-4 block.

The crane 139671 replaces the 139741. The 139021 is a couple of degrees smaller.

I built a very similar engine for a customer several years ago. It is a 540, 990 heads w/bowl blend, air gap dual plane intake, 9022 holley, stainless marine exhaust. The cam is a Comp hydraulic roller. Cam is Comp XM284HR 230/236 w/112 LSA. It made 490 HP at the PROP at 5300 rpm. Peak torque was at 3800 rpm. 490 PSHP is right at 550 at the flywheel. We chose such a conservative cam and intake setup because this is in a Sea Ray deck boat with a Bravo 3 drive. We wanted a torque monster. A larger cam and single plane intake should put that engine near 600 HP. Looking at the torque peak it's obviously under cammed for optimum HP, and that cam is larger than the 731.