Are you looking to find living relatives in Punitz who share the Messenlechner blood line with you? In this case, I can't see what the Diocesan Archive could do for you. It might be more expedient to write to the town hall (Bürgermeisteramt) in Punitz. As far as I know, the Archive has no capacity for doing searches. They make only lookups in the records if you can provide the name and the date. But I don't want to stop you. If you write to Punitz, mention the house numbers and ask whether the house numbers are still the same as in the 19th century.
You mention numbers 38 and 39. However, the houselist of 1858 at the BB web site mentions 39 and 40 as occupied or owned by Messenlechners. Maybe besides writing to the Bürgermeister, you could write to "Die Familie wohnhaft in Haus No. 39 (or 40)" in Punitz.
If you have time, you could look through the civil records filmed by LDS. Right now I don't know where the civil records were written of Punitz. Maybe under Güssing or under the "Environs of Güssing" recordings. Start with births in 1920 (the most recent records) and look for recordings of Punitz with last name Messenlehner or Messenlechner, as well as for house numbers 39 and 40. If a person was born between 1900 and 1920, he or she might have been known to people born in the 1940s or 50s who still live today and may know who and where the descendents are now.