I will make up a pdf with some images and dimensions, which will probably better illustrate what I did. I am in the process of remaking the after toe rails which are a different construction, and include details of those as well. Iroko is very brittle to work with and wouldn’t be suitable for the whole structure. For the inner core I used a number of small sections to manage the curves of the substructure, then overlaid the longer pieces of teak. There may be an alternative to using teak, such as Flexiteak but you are probably best talking to the manufacturers, and a shipwright. I chose go down the like for like route for simplicity and longevity. I invested in a table saw and a mitre saw both which were essential in ripping down the timber and getting angles right.