It does exist, but it is greatly varied by various lines. Remnants of it can be found in the various lineages that claim direct lineage to Huang Hua Bao and Da Hua Mian Jin.
Short forms preserved:
1. La Jian Chui - Stretching Arrow Strike
2. Shier Sanshi - 12 Loose Techniques
3. Lian Huan Kou Da - Linked Capture & Strike
4. Shisan Sanshi - 13 Loose Techniques
5. Shiba Sanshi - 18 Loose Techniques
6. Jian Quan - Arrow Fist
7. Shiliu Sanshi - 16 Loose Techniques
Long forms preserved:
1. Xiao Ba Gua Quan - Small 8 Diagrams Fist
2. Ba Gua Quan - 8 Diagrams Fist
3. Jian Zhang Quan - Arrow Palm Fist
4. Zhuang Kuang Quan - Post Frame Fist
5. Zhuang Quan - Post Fist
6. Si Men Quan - 4 Gates Fist
7. Hua Quan - Flower/Variegated Fist
8. Shiyi Shou Quan - 11 Hands Fist
9. San Bei Fo Quan - 3 Prayers to Buddha Fist
10. Qiang Bao Zhang Quan - Mast Bag Palm Fist
All of these forms and sets can be accurately traced back to Huang Hua Bao or Da Hua Mian Jin and as such are considered ancestral. All other forms and sets outside of the above listed and the 3 standard (Xiao Lian Tou Quan, Chen Qiao Quan & Biao Zhi Quan) are considered modern developments coming into existence after the 1940's by either creation or imported from outside arts. Weapons sets and the Post(s) were poorly organized and not codified in any sense of a "form" until approximately the 1930's, hence the overflow of extra material found in the sets and forms presented above. After the codification of the post and weapons many of these patterns disappeared from several lineages in their ancestral form. Some lineages, though did retain them.
Most of the long forms are simply a collection of the loose material and the shorter "unfinished" sets, some are simply elaborations on the 3 sections of the first set Xiao Lian Tou Quan. Mostly what they have to offer is further exploration of certain concepts and/or footwork. Yong Chun was originally a very simplistic art based on approximately 48 techniques bound and linked by various concepts, principles and theories. As with many systems of TMA "Forms" were simply a collection of loose techniques and theoretical approach, to be composed/choreographed into a "Set" once the adept had learned all the movements and theory. This is known as Kuang Lian (Frame Training) and is an old TMA concept that stems from military training. This can clearly be seen in Northern Chinese systems as well as in Okinawan Kata, ever wonder why two or more lineages that trained under the same master have two Taolu/Kata that are recognizable yet vary in length and choreography? Some of this is undoubtedly alterations made by those that passed it on but also because of the old "Frame Training" method that used to be prevalent before the WWI. The British aristocracy and the opera had a lot to do with the standardization of Taolu for performance reasons.
Irregardless these sets will offer little to individuals that learned a "completed" version of Yong Chun, for those who "didn't" they may offer some insight into various concepts. I for one have learned some of these sets and find them interesting and worthwhile, others may not, to each their own.