Arrival Lufthansa in PEK, 10:35 at T3 _ Dep. from PEK to Chengdu 13:00, at T3- transfer enough?

Yes, the time is enough and the procedures are as follow.
Arrive at the International Arrival Level at 3F of T3-E
→ accept Health & Quarantine
→ Inspection
→ go through the Entry Frontier Inspection
→ take APM at 2F of T3-E to reach 2F of T3-C
→ go to the International Baggage Claim Hall
→ go through the Animal & Plant Quarantine (sample check)
→ accept the Customs Inspection located north of the International Baggage Claim Hall
→ enter into the I-D Transfer Hall
→ finish domestic flights transfer procedures & deliver baggage
→ take the special elevator upstairs to 3F of T3-C
→ pass the Domestic Security Inspection
→Waiting & boarding