Rem top speed is an unrequired side 'symtom' of being able to have good reserve power at normal cruise speeds and hitting a chop/ wake stalling etc...
Also ball park for these trailer 4.6m thru around 6m min well powered around 42mph and well powered high 40s around 47/48 mph and propped at full normal load to middle or smidgen below the manufactures max rpm range..
So on 1050kg
WoT for 42 mph is about 100hp
Propped well.. pitch and good slip (grip) cruise around 4000 rpms around 32 mph
for 47 mph 118 hp
cruise around 3850 rpm around 37 mph on flat water.
If go larger engine and cruise at smaller engine speed (32mph) you will have around an extra 7 to 12% better economy...
cruise at the faster speed and around 5 to 7% more fuel than the smaller engine at slower cruise speed.
Get in heavey chop on the smaller engine you will be working the throttle a little to stay on plain, and crew thru more gas..
On the larger engine you will not have to work the throttle.. set and go..travel more comfortable at a 2 to 3 mph faster and the fuel consumption drops dramatically to well below the normal slow cruise.
Put a little more weight in , say extra guy and gear , say 90 to 110 kg, the smaller engine will cruise couple mph slower, use more fuel, more 'pig' in chop.
larger engine, hardly notice the diff, 50 to 75 rpms to maintain same cruise speed, stuff all change in consumption. And heavy chop, no change other than the extra weight will improve ride a little more.
Over power say plus another 10 hp and all the benefits of the larger engine get better....just get in the habit that every time you take off, "all holding on?"
Cause you will be just in gear, trimmed right down, ask, move throttle, a little forward, let it go, as goes over the bow wave trim up and will be at 3800/ 4000 cruise speed...and have not touched the throttle.
If they are not holding on they will be on the floor or over the back... little over stated but certainly applies.
I have a lot ppl contact me .. "my boat is not going as well as the original (sales) sea trial... (not fully loaded) can you see if propped right?"
8 times out of 10 it is
1 time, a sight change makes an improvement but not significant to warrant the capital cost of a new prop
Other time is baddly propped , but still cant fix being min to under powered.
Also of interest, several hull manufacturers, often with a small charge, will increase the load tags for a little more hp for insurance purposes...I assume therefore there tends to be a substantial margin in some hulls.