i would suggest using bzp m12 coach bolts or studding. use a large plated washer also. offset the bolts from the center line also to spread the compression which will help to minimise any splitting if the timber moisture content reduces in the new timber.
mark
If you type the key words of your question into our search box to the left of the site you may find the answer is already posted or is in the DIY projects section of the website. Every post goes through a monitoring process and using the search box may speed up your answer.