Hello,
To estimate SBP and DPB by PTT method, first you need to accurately detect the R peak. Then measure the time difference between the R-peak and the start of PPG pressure rise. Then you can use the existing equations (some simple some more complex) to estimate the SBP and DBP.
Anyway, I am a professional Biomedical Engineer and have done similar jobs with ECG, PPG and the MAX sensor (MAX30102). I can do your project completely. My price and timing are only placeholders here and will depend on the actual amount of work. Thanks.