This is the place to start looking for experimental conditions: https://www.thevespiary.org/rhodium/Rhodium/chemistry/redamin.titanium.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/redamin.titanium.html)
Titanium isopropoxide is a great catalyst for reductive aminations with NaBH4, and at the same time it is not acidic, and will therefore not cause any great pictet-spengler side reactions. Of course, instead of using a large excess of amine over carbonyl compound as in the examples in the text, you should instead use an excess of formalin over tryptamine, say 40 mmol of HCOH, 10 mmol tryptamine and 20-40 mmol Ti(iPrO)4.