For want of wood, I've decided to pontificate a bit instead.
Since some questions have been asked about scratch building in the past, I thought I'd try to demonstrate my own, idiosyncratic methods. Not that I'm setting myself up as any sort of expert 'cause I'm not. However, I wanted to show that you can, to an extent, make things up as you go along.
So, here's how I put the deck beams in for a raked deck without any plans for such a thing.

First, I laid a long straight piece of precision equipment (aka a spruce spar) along the centre line of the deck.

Doing this shows how much rise the deck needs to have from the gunwales to the centre. Having already cut seats in the gunwales for the deck beams, I inserted various thinknesses (why doesn't the spell-checker like this word?) of "stuff" under the beam until I found one that was just right...not too hot and not too cold.

This 'Goldilocks stuff' was then restrained across the hull next to the deck beam position.

This gives us a level to which the deck beams should be angled. Here they can be seen very badly cut out and fitted so as to be level with the top of the guide strip.

Extra slots have been cut for the lengthways spars and glue applied.

And this is where I was when the wood ran out

The half card circle shows the shape of the front of the cockpit. It'll run right back to the rear cross-member.
And with that, I shall shut up. Appologies if you've heard it all before or were offended by either my method or presumption.
Have a good weekend!